Abstract
In explaining Iron Age archeology, the study of metal artifacts is of particular importance because of the hidden technical values. The study of metalworking methods enhances our understanding of the industrial centers of metallurgy, stylistics, and available mines. The purpose of this study is to identify the methods of construction and elemental analysis of “ornaments” discovered from “Iron Age” sites in northwestern Iran, using metallographic experiments and an SEM-EDS elemental analysis device. In the Iron Age, the making of metal objects, especially those with many ornaments, flourished. Therefore, knowing the manufacturing methods and the type of alloy used in them is one of the essentials of this research. This research responds to the question, what methods used to make the discovered ornaments from the Iron Age sites in the northwest? Or what were the most used elements in the construction of these objects? In these areas, the current research hypothesis is that most of the “ornaments” made by hot hammering and casting methods and have a large amount of tin in their structure, which uses for greater strength and flexibility of copper and tin (bronze) alloys. In this study, several samples of ornaments discovered from Iron Age sites in northwestern Iran, which were geographically very close to each other, were tested by metallography and elemental analysis. In this experiment, using a scanning electron microscope equipped with an SEM-EDS element analyzer, making these metal objects and their constituent elements were determined. This study shows that the main methods of making these metal objects have been hot hammering, but those objects that had a large volume made using the casting method. Also, the most used element to increase the strength and flexibility of objects is the element of tin. 
Keywords: Iron Age, Northwest of Iran, Bronze Objects, Metallography, SEM-EDS.

Introduction
In the Iron Age areas of the northwest, metalworking was done at an advanced level. The expansion of the tradition of metalworking in the northwest can be seen in other Iron Age areas of Iran. (Talaei, 2001:77-83) One of the reasons for the development of metalworking in the Iron Age areas of northwestern Iran has been the abundance of copper and iron ore mines in this region. During the excavations of the Hasanlu area in the south of Lake Urmia, founded a large number of iron and bronze objects. The large volume of metal objects discovered in the Hasanlu area indicates the prevalence of metalwork in this region of the Iranian plateau. (Pigott, 1989: 67-79) According to the studies, the residents of Hasanlu have supplied their required copper ore and iron ore from the mines that probably existed around this area. The development of metalworking art in this region, in addition to the existence of metal mines and fuel reserves, has been the development of furnaces and metal smelting molds, which in some Iron Age sites such as Hasanlu, obtained a large number of these metal smelting molds. The main reasons for the development of technology and style of metal products in northwestern Iran in the Iron Age could have been powerful governments such as Urartians and Manas. (Aliun and Sadraei, 2011) They were skilled metalworkers in the vicinity of Iron Age sites. One of the signs of this effect is discovering a bronze bracelet discovered in the Toul Talesh cemetery in northern Iran, which shows the expansion of Urartian territory in this region. There is a Urartian cuneiform inscription on it. This inscription shows that Argishti II, King of Urartu, gave this bracelet to Khaledi God. This person could have been a prince or a military person. (Tahmasebi and Masoudi Nia, 2015) The main issue of this research is to know the construction methods and the constituent elements of the jewelry discovered from the northwestern region of Iran. In the Iron Age, especially the Seldouz valley, these sites are primarily located in the Seldoz Valley and are geographically very close to each other, which can help understand the methods of construction and elemental analysis of the metal samples tested. The present research has been done by analytical-experimental method and based on scientific and laboratory studies. The purpose of this study is to identify the methods of construction and elemental analysis of “ornaments” discovered from “Iron Age” sites in northwestern Iran, using metallographic experiments and an SEM-EDS elemental analysis device. This research responds to the question, what methods used to make the discovered ornaments from the Iron Age sites in the northwest? Or what were the most used elements in the construction of these objects? In these areas, the current research hypothesis is that most of the “ornaments” made by hot hammering and casting methods and have a large amount of tin in their structure, which uses for greater strength and flexibility of copper and tin (bronze) alloys.

Materials and Methods 
In this research, the first eight metal samples from different Iron Age sites in northwestern Iran were collected through the reservoir of the National Museum of Tehran and sampled in the same place, and then sent to the Materials and Metallurgy Laboratory of the Sharif University of Technology for metallographic testing.

Discussion
Laboratory analysis and elemental analysis of metal samples using the SEM-EDS method show that a small amount of arsenic was founded in the alloy composition of the samples Because most copper metal ores before extraction and smelting contain amounts of arsenic. Therefore, there is a possibility of the unintentional existence of arsenic in the composition of these metals. Another element that a large percentage obtained in the composition of these metal samples is tin. Metallographic images of the ML-98-7 and ML-98-8 specimens show that these two specimens have a branched or dendritic structure in their body and are made by casting. Also, tiny cracks on the metallographic images of ML-98-2-ML-98-3 and ML-98-6 samples formed due to stress and fatigue caused by continuous hammering work on these metal works. The dark spots seen in most of these microscopic images indicate oxygen, carbon, and a lack of copper and tin, which have caused corrosion and sulfidation of these metal objects.

Conclusion
The results from the images obtained by scanning electron microscopy equipped with an SEM-EDS device found that the metal samples have a relatively large amount of tin. A small percentage of arsenic found in the metal samples tested. Considering the amount of arsenic in these samples can be concluded that metalworkers of this period may not have noticed the harms of using arsenic at that time and therefore used this element to improve the properties of bronze alloy. Ancient metalworkers used tin, arsenic, and antimony elements in the composition of bronze alloys to increase the hardness of the work. The items in the category of jewelry need to pay more to get the right shape. Another possibility is the unintentional presence of arsenic. The presence of large amounts of tin in these samples indicates that arsenic may have been naturally present in copper ores and Ancient metalworkers used tin to lower the melting point of copper and increase its strength and flexibility. Microscopic studies of bronze objects show that many copper sulfide compounds are present in metal samples. The presence of copper sulfide inclusions dispersed on the surface of the metal matrix and stretched in the longitudinal direction of the microstructure of ancient copper alloys may indicate the use of oxide ores along with some copper sulfide ores for extraction. Most of the ornaments found in the northwestern Iron Age sites, such as bracelets and collars, were made by hot hammering, subsequent hammering or forging, and objects with larger volumes and decorations molded by casting. In general, the objects discovered from the Iron Age sites in the northwest, especially the Hassanlou site, are more complex in terms of technique and construction style than the Iron Age sites in other parts of Iran, where existed local and indigenous governments. This issue has been due to the proximity of northwestern Iran to powerful governments such as Urartu and Manna.

Abstract
The Kurgan and the megalith tombs were common graves in the Bronze and Iron Ages. The vast geographical area is central Europe, central Asia, Anatolia, and Northwest Iran. The size of Kurgans and the objects discovered from these graves represented the deceased’s social status. Animal burial was also common in the late second millennium BC in the Caucasus, Eastern Anatolia, and Northwest Iran. This study explains the Kurgans, megalith tombs, and the traditional victim animals for particular social classes in the Bronze Age. One of the questions in this research is about trade relations between the South Caucasus and Northwest Iran in the Bronze Age. And why the Kurgans of this period in size and number of objects discovered inside graves differ. In answer to these questions, the represented research hypothesis found the Obsidian bows and Urmia ware of the Bronze Age in northwestern Iran. In this period, close relations existed between the South Caucasus and the Northwest of Iran. Also, the large size of the Kurgans and the objects discovered inside these graves represented the deceased’s social status. Ordinary people had a simple coffin grave, and their graves had no funeral gifts. But the high-ranking people in this community have huge graves and, along with the owner, discovered a lot of funeral gifts.  The Kurgans of the South Caucasus and Northwest of Iran were studied using observation and library surveys. The results show that the Kurgans discovered in the South Caucasus are older than those in the Northwest of Iran, and in the Late Bronze Age, there was a cultural and commercial connection between the two regions. In the Late Bronze Age, most Kurgans were discovered in the Aslandooz and Pars Abad in Ardabil, Ahar, and Khodaafarin in Eastern Azerbaijan. Most of them had a circular shape, and many of these graves found animals deceased, such as cows, horses, and dogs, with funeral gifts.  
Keywords: Bronze Age, Kurgan, Megalith Tombs, South Caucasus.

Introduction
According to archaeological findings in the Bronze Age, due to migrations and close relations, various developments happened between the Caucasus and northwestern Iran, especially in the burial tradition in the Bronze Age sites of Northwestern Iran. The Kurgans were formed from the late Chalcolithic Age to the Iron Age in a wide geographical area, including the Southern Caucasus, Eastern Anatolia, and Northwestern Iran. However, most Kurgans are chronologically related to the Bronze Age and Iron Ages. These tombs were by people who lived in semi-permanent settlements in the geographical area of steppe plains, extensive pastures, grasslands, and forests.
Animal burials are the essential issues in these Kurgans. According to studies on Kurgans from the Southern Caucasus and Northwestern Iran, animal burials, including horses, cows, and dogs, have been found in most large-sized Kurgans (Rudenko, 1953: 53-60). The graves in which animal burials show that the owner of these graves had a high social position. 
The lack of knowledge in this study is limited to the Kurgans of the Bronze Age in northwestern Iran. For this reason, one of the innovations in this study is a careful study of Bronze Age Kurgans in Northwestern Iran, especially the late Bronze. This research investigates the Kurgans discovered in the South Caucasus and Northwest Iran during the Bronze Age using objective observation and library studies. Most of the research done in the late Bronze Age Kurgans of Iran is based on field surveys and documenting and collecting the necessary information. 

The Kurgans of the Southern Caucasus region
The oldest Kurgans are in Asia Minor, the Balkan, and the Caucasus. These Kurgans are related to the fourth and third millennium BC. The oldest Kurgan belongs to the fourth millennium BC in the Caucasus region. The Scythians learned this burial method from the native inhabitant, and in combination with their belief, they gave it a shape that is today known as Tomolus (Firouzmandi, 2015: 157). There are two types of tombs: simple tombs that belonged to ordinary people and luxurious tombs that belonged to princes and kings. These Kurgans contained wooden structures and, with great skill, were made, which included pottery, war tools, and ornaments (Gershevitch, 1993: 189). Several Kurgans belong to the Kura-Aras culture in the Shanghvit area and other parts of Armenia in the Southern Caucasus. These Kurgans belong to the Early Bronze Age to the Middle Bronze Age. These Kurgans are very large and similar to those found in Armenia and Georgia. Objects such as pottery, gold, and other things have been found inside these Kurgans.

The Kurgans of Northwestern Iran
Khorramabad cemetery in Ardabil is one of the ancient sites of Northwestern Iran. Kurgans and large stone tombs have been discovered at this site. This cemetery belongs to the Late Bronze and Iron Ages. In another of these graves, which is unique, the remains of 34 horses have been found. The main Kurgan has found various types of Gold, Bronze, Iron, Stone, Glass objects, and pottery.
The Zardkhaneh site of Ahar, which belonged to the Late Bronze Age, is one of the essential sites in Northwestern Iran. From this site, there are 95 Kurgans and large stone graves. These graves are like the Kurgans and large stone graves of Azerbaijan, Armenia, and Turkey. These tombs have many grey and brown potteries with bronze and stone objects.

Division of Kurgans and large stone tombs in Northwestern Iran
Simple Chinese stone tombs: These graves are constructed of large stone and are covered with soil about half a meter from the surrounding lands. The direction of the graves was east to West (author).

Box tombs: These tombs consist of large stones. These types of graves are recognizable as mounds of soil. A raised stone with carved motifs was placed vertically on top of the tombs (author).
 
Kurgans: Kurgans in archaeology are called cone-shaped tombs. These tombs are known as plains steppe pyramids. There are several Kurgans in the Aslamdooz of Pars Abad. These tombs are about 10 to 14 meters in diameter and 5/3 to 4 meters high (author).

Discussion 
The burial traditions of the people in the Bronze Age show a general understanding of their beliefs at that time. Based on excavations in the northwest of Iran, various burial methods have been identified, and each of these patterns followed the people’s worldview. Megalithic stones and Kurgans appeared for the first time in the South Caucasus region. They later became popular in this region as a cultural connection with neighboring areas in the Northwest of Iran. Kurgans had a rectangular room consisting of the main chamber of the Kurgans, and around it, they lay stones in a circle. The shape of the circle was a sacred symbol in the past. For this reason, since prehistoric times, the circle motif has been used on pottery, metal objects, architectural structures, and in constructing Kurgans and megalithic tombs in the Bronze Age.

Conclusion
Based on the study, most Kurgans have been discovered from outside the current borders of Iran related to the Early and Middle Bronze Age and are larger than the Kurgans found in Iran. While most of the Kurgans and large stone tombs belong to the Late Bronze Age and Early Iron Age, most are in Eastern Azerbaijan and Ardabil in Northwestern Iran. Kurgans and large stone tombs in this area and the shape and burial objects inside these tombs are similar to the large stone tombs found in the Southern Caucasus, especially in Armenia and the Republic of Azerbaijan. Additional evidence related to the stelae or raised stone tombs was found on the Ardabil plain in the Late Bronze Age. There are carved animal motifs on these stones. These raised stones belonged to Bronze Age sites in Azerbaijan and Kazakhstan. Inside tombs of the Zardkhaneh site in Ahar are Urmia potteries, and samples of these potteries have been discovered in Kura-Aras cultures in Armenia and the Republic of Azerbaijan. Another Bronze Age site in Northwestern Iran with shiny grey pottery is the Buini Yughun site in the Nir area, similar to the Urmia potteries. In the Southern Caucasus, Anatolia, and Northwestern Iran, the Bronze Age was characterized by mass metal production, trade with the neighboring area, economic growth, construction of military buildings, and large stone tombs. The discovery of valuable objects in this period shows these societies’ high economic and social levels in the Bronze Age. One of the essential pieces of evidence is the discovery of the arrowhead of the Obsidian in the Zardkhaneh site of Ahar. The discovery of the Urmia potteries and Obsidian in the Bronze Age shows trade relations between Northwestern Iran and the Southern Caucasus in the Late Bronze Age.