There was another reason. Uriankhai trade with Russians was conducted on credit using a complex system of valuation principally pegged to squirrel skins. As the number of squirrels declined because of over-hunting, the price of goods increased. The Russians also manipulated the trade by encouraging credit purchases at usurious rates of interest. If repayment were not forthcoming, Russian merchants would drive off the livestock either of the debtor or of his relatives or friends. This resulted in retaliatory raids by the Uriankhai.