The majority of ink spilled over the Kushan Empire has been concerned with chronology. When did the Kushan Empire happen? It remains an important question, and many specialists in other fields have an erroneous view of the Kushan Empire, seeing it as encompassing the first to third centuries. However, amongst specialists there is no longer much disagreement. Certainly the margin of error for the reigns of kings is large, at about 20 years, but it the same margin of error applies, independently established, for each of the thirteen Emperor's who make up the dynasty.
To avoid a stale and pointless debate those involved in Kushan studies need to find new questions to answer, new problems to engage with. This could mean moving beyond political history to try and understand economic, or social realities in the Kushan period. It could also mean expanding the horizons of Kushan political history. One of the ways that can be done is to ask questions about geography, the physical space the Empire occupied over time. In order to examine that problem new sorts of evidence have to be examined. The marks a political entity leaves behind. This could mean accounts in texts, such as the Chinese chroniclers, Buddhist pilgrims, or much later historians from Kashmir. It could also mean the claims made by King's about the extent of their dominion. In that regard the Rabatak inscription of Kanishka must be mentioned, but also the testaments of Rudraman and Samudragupta. It might mean finds of seals, royal buildings, dynastic shrines. It certainly means the acknowledgement of kings in private inscriptions. But what it mostly means is coin.
Coinage is a political marker. And the most ubiquitous available to us. Though the majority of archaeological sites do not yield coins (in a survey of sites in Afghanistan Ball listed X sites of the Kushan period which yielded no coins) more do than any other sort of political marker by a wide margin. And coins are not recovered exclusively from sites. They are frequently found in hoards, buried by their original owners for safe-keeping in a place often removed from ancient settlements.
Presented here are three lists of potential use in exploring the Geography of the Kushans. The first is a list of sites culled from archaeological reports. These are sites which have yielded some political marker, coins in almost every case, but sometimes inscriptions. There are nearly a hundred such sites, but students of Kushan history will find them frustrating. Archaeologists, with some notable exceptions, have not shown much interest in the proper publication of data. Digging, rather than reporting, is the preferred mode of operation. Even when a report is published it is frequently so summary as to serve no useful purpose. This is particularly acute in India, where under the ASI a particular form of reporting which privileges a pre-conceived interpretation over reporting the data has taken deep roots. I would be surprised if the sites here represent one-tenth of the sites that have actually been dug, and less than one-tenth of those here are in enough detail to be of use to a historian.
More useful, and helpful in illustrating the tiny fragments upon which historians interpretations are based, are surveys. For example, a survey undertaken by Ali (2001) in the Mardan district of Pakistan revealed 402 sites, compared to the 13 sites in the district which have been excavated, studied, and protected. The survey has a purpose. It gives archaeologists a list of future sites they might investigate and allows them to make informed decisions about field work. Unfortunately surveys are very cursory examinations of sites, so they often miss things, and the desire to report them in a realistic space results in brief summaries. So, we know Ali's survey found coins at a number of sites, and that they found at least one imitation Huvishka coin - but we don't know which site it came from or what the other coins were. The survey tells us that there are 402 additional sites we don't know anything about but history must be based on the 13 sites we do.
The second two files cover coin hoards, one covers hoards of gold coins and the other copper coins. The publication of hoards is not much better than that of sites. I will make no claim that these lists are complete. They could be supplemented and I would encourage readers who spot omissions and errors to contact me. However, anyone who has studied coin distribution for other parts of the world will be amazed at just how little material is available. This likely reflects a lack of reporting resulting from the illegal trade in Indian and Central Asian coinage, a problem that seems intractable. In one important respect they are deliberately incomplete. Items that might be considered numismatic 'folk-lore' such as single coin finds, items purchased or reported to come from a district, are excluded. Such things have been deliberately excluded from the categories here. While useful in the early stages of research they are shifting sands on which to rest interpretation. For example, all the items listed for Bengal by Gupta (1953: 29) would fall into such a category.
Collecting this data in one place, in a dynamic media, makes it accessible (or at least more so than dispersed amonst reports). However, primary sources do not interpret themselves. Nor do they 'speak' to the historian as tradition would have it. The real difficulty is establishing what this means. Coins can move enormous differences. It is frequently stated that copper coins did not travel far, that they are therefore good indicators of political boundaries. A cursory glance through the data (for example the site of Vaisali) shows coins even copper coins moved thousands of miles. It is frequently assumed that coins were deposited close to the date at which they produced. So, if an archaeologist finds coins of Kanishka they can assume the coins were deposited in the reign of Kanishka, and thus that the site was active in the time of Kanishka. Again, even in the limited data here (see for example Rang Mahal or Patna) this historian can find plenty of evidence that coins were deposited centuries after they were produced.