Abstract
Understanding burial methods and interpreting how grave goods reflect the culture and beliefs about the afterlife, can give insight into past customs, religious beliefs, as well as social structures and complexities. With the emergence of urban centers and their expansion during the Early and Middle Bronze Ages, extensive trade relations and unique cultural interactions formed between the most important cultural hubs of the Iranian Plateau and Central Asia. This continued into the Late Bronze Age with the emergence of the Bactria-Margiana Archaeological Complex (BMAC)/Greater Khorasan Culture (GKC). During this period, specific burial traditions developed, the most important of which is the cenotaph. Understanding the general origin of cenotaphs is one of the main goals of the present research. These are graves that lack the skeletal remains of the deceased and likely served a memorial function. The formation of this tradition has been reported from the Early Bronze Age in southeastern Iran, in the cemeteries of Shahr-i Sokhta, Shahdad, and Khunaman. In later periods, namely the Middle and Late Bronze Ages, it emerges as a widespread phenomenon in the eastern half of Iran and Central Asia. In this regard, the main research question is the “why” and “how” of this phenomenon and the mechanisms of its spread. The volume and number of cenotaphs excavated in numerous cultural regions and their provided chronologies help in analyzing the topic. The general hypothesis is based on the logic that, considering the quantitative and chronological analysis of the statistical population, the main origin of this tradition or burial method is attributed to the southeastern region of Iran, specifically the Early Bronze Age and the site of Shahr-i Sokhta in Sistan. This tradition then became prevalent in the Middle Bronze Age in the Khunaman and Shahdad cemeteries of Kerman and, finally, in line with cultural communications, the movement of people and ideas through the mechanisms of communication networks, indirect trade, and nomadic craftspeople, it spread widely in the regions of Central Asia during the Late Bronze Age.
Keywords:  Bactria-Margiana Archaeological Complex/Greater Khorasan, Shahr-i Sokhta, Shahdad, Burial Traditions, Cenotaph.
 
1. Introduction
Understanding burial practices is crucial for deciphering the intangible dimensions of prehistoric cultures, reflecting the thoughts and socio-cultural structures of human societies. Graves hold significant archaeological, sociological, and anthropological information, providing valuable insights into the non-material aspects of past cultures. While archaeologists cannot fully reconstruct all facets and ideologies of human societies based solely on burial studies, recognizing burial methods and interpreting grave goods significantly illuminates the importance of interment, philosophical concepts regarding the afterlife, customs, religious beliefs, and social structures and complexities. The emergence of a novel type of grave lacking human remains the cenotaph represents a prevalent burial method in the Middle Asian region (including eastern Iran, Central Asia, Pakistan, Balochistan, the Makran region, and the coasts of the Persian Gulf and the Sea of Oman). These are tombs without bodies, likely serving a memorial function and containing only grave goods. Known examples of cenotaphs in the southeast date back to the Early Bronze Age from Shahr-i Sokhta, Shahdad, and Khunaman. In northeastern Iran and Central Asia, they are reported in the Late Bronze Age and are considered characteristic of the Bactria-Margiana Archaeological Complex (BMAC)/Greater Khorasan Culture (GKC). However, understanding the origins of the human communities associated with this culture and its characteristics remains a key unanswered question. Due to insufficient information and understanding of this burial tradition, and the lack of similar examples during the excavation of cemeteries like Khunaman and Shahdad, early excavators attributed the absence of skeletal remains to post-depositional processes such as water erosion from seasonal streams, soil salinity, and wind erosion. Diffusionist perspectives often attribute the origin of eastern Iranian cenotaphs to the BMAC/GKC, although their roots might be found in southeastern Iran during the Early Bronze Age.
 
2. Materials and Methods
The main objectives of the present research are to gain a general understanding of the origin of cenotaphs discovered in southeastern Iran during the Early to Middle Bronze Age, and subsequently their distribution across a wide area of eastern Iran, Central Asia, Afghanistan, Pakistan, the coasts of the Persian Gulf, and the Makran region during the Late Bronze Age. Today, this burial tradition is recognized as part of the burial customs of Central Asia and Khorasan, particularly within the BMAC/GKC. 
 
3. Data
The study of cenotaphs and their origins in the southern region is a relatively new topic, with the statistical population comprising cenotaphs unearthed from the excavations of Shahr-i Sokhta, Shahdad, and Khunaman. At Shahr-i Sokhta, six Early Bronze Age cenotaphs have been identified and analyzed as such by excavators (Seyed-Sajjadi, 2007: 122). The Shahdad cemetery was excavated over seven seasons between 1966-1976 CE by Ali Hakemi, followed by an additional season under Mir Abedin Kaboli in 1977 CE (see Eskandari, 2019: 64). According to Hakemi’s report, a total of 383 graves were excavated at Shahdad, the majority of which lacked skeletal remains, and many others contained only partial skeletal remains (Hakemi, 1997). In the Khunaman cemetery of Kerman, artifacts were discovered around the 1950s CE during earthmoving operations for the construction of a residence. Some of these artifacts were transferred to the British Museum, and a number are currently held in the Kerman Regional Museum. Subsequently, in the 1950s and 1960s CE, researchers’ attention was drawn back to the Khunaman cemetery, where John Curtis, after re-examining the absence of skeletal remains in the graves, did not consider it a significant issue, attributing the lack to post-depositional processes caused by natural factors, similar to the interpretation at Shahdad (Curtis, 1988). It is worth noting that related studies in northeastern Iran have also made attempts to study and determine the origins of cenotaphs (Iravani and Tahamsebi, 2018; Basafa, 2016).
 
4. Discussion
The discussion and analysis regarding the origin of cenotaphs and ideological issues indicate that this burial tradition without skeletal remains, likely with a memorial function, became prevalent in vast areas of eastern Iran, the Indus Valley, and Central Asia in the second half of the 2nd millennium BCE, coinciding with the Late Bronze Age and the BMAC/GKC. Although some attribute its origin to this culture and believe it spread to other regions, studies show that cenotaphs were first identified in southeastern Iran at the Shahdad site, dating back to the Early and Middle Bronze Ages. At that time, a lack of sufficient knowledge led excavators to attribute the absence of skeletal remains to natural factors such as floods and erosion.
Similar findings are observed in Khunaman, Kerman, indicating cultural homogeneity. In addition to southeastern Iran, pit-grave cenotaphs related to the Early and Middle Bronze Ages have also been discovered at Shahr-i Sokhta in Sistan. In Central Asia, at sites like Gonur Depe and Ulug Depe, cenotaphs with catacomb, cist, and pit-grave structures with specific Late Bronze Age architecture have been found. In Khorasan and the northeast, examples of simple and burnt pit-grave cenotaphs have also been identified at sites such as Tepe Hissar and Shahrak-e Firozeh.
The abundance of cenotaphs at Shahdad is significantly higher than in other regions, and their chronology, dating from 3100 to 1900 BCE, suggests deep roots of this tradition in southeastern Iran. Challenges related to the lack of proper understanding of the cenotaph burial pattern and insufficient reporting in early excavations at Shahdad and Khunaman are also evident.
Considering the extensive Bronze Age trade connections between Central Asian urban centers and the hubs of Shahdad and Shahr-i Sokhta, cultural similarities, including the cenotaph burial method, have led to hypotheses regarding migration or cultural exchange. The importance of cenotaphs increases in the Late Bronze Age in the northeast and Central Asia, but their prevalence in Central Asian sites such as Gonur Depe is relatively low. This, considering the chronology, suggests that southeastern Iran was likely the primary origin of this phenomenon. The discovery of cenotaphs at Gonur Depe in Turkmenistan, a major center of the BMAC, shows a close connection with Shahdad in southeastern Iran, with the difference that Gonur Depe examples are limited to the Late Bronze Age, while those at Shahdad date back to the Early and Middle Bronze Ages.
From an ideological perspective, it appears that new rituals and beliefs emerged in the Late Bronze Age. Sarianidi associates the burials of Gonur Depe with Zoroastrian ideas, considering Zoroastrian doctrines regarding the non-pollution of earth and specific mortuary practices. Innovations in the structure of cenotaphs are also observed in the Late Bronze Age; for instance, while Shahdad features pit-grave structures, Gonur Depe exhibits cist and catacomb cenotaphs, indicating the evolution of this burial tradition based on the customs and ideologies of different Central Asian societies.
 
5. Conclusion
The cenotaph burial practice, prevalent across eastern Iran, Central Asia, and the Indus Valley within the BMAC/GKC sphere during the Late Bronze Age, has been investigated for its origins based on excavated numbers, chronologies, and grave structures. This study reveals the cenotaph burial tradition as indigenous to southeastern Iran, notably at Shahr-i Sokhta (Early Bronze Age) and the Khunaman and Shahdad cemeteries (Early and Middle Bronze Ages). Through various, not fully understood mechanisms including migration, political alliances, mobile specialists, and the transmission of beliefs and ideologies via networks this tradition widely diffused into BMAC-influenced regions during the Late Bronze Age. Over time, it integrated with local customs and structures, culminating in innovative burial forms like cist and catacomb cenotaphs in Turkmenistan, particularly at Gonur Depe. Challenging the traditionally unidirectional view of BMAC/GKC interactions, recent archaeological studies in eastern Iran suggest a re-evaluation, proposing potential influences from the Iranian plateau towards Central Asia during the Late Bronze Age. Previous research on BMAC/GKC cultural connections focused on iconography and homogeneous prestige goods from burial contexts. This research infers the indigenous origin of the cenotaph burial culture throughout the Bronze Age phases in southeastern Iran, specifically at Shahr-i Sokhta and prominently at Shahdad. Through diffusion and communication, encompassing both material (burial structures) and spiritual (customs and ideologies) aspects, this practice influenced neighboring regions, notably Central Asia and areas under BMAC influence in eastern Iran and Central Asia. This highlights a potentially more complex and multi-directional interaction between these cultural spheres than previously assumed.