Commercial credit and agricultural consumer loans were the main types of loans. The trade credit was usually extended by temples in order to finance trade expeditions and was nominated in silver. The interest rate was set at 1/60 a month (one shekel per mina) some time before 2000 BC and it remained at that level for about two thousand years. Rural loans commonly arose as a result of unpaid obligations due to an institution (such as a temple), in this case the arrears were considered to be lent to the debtor. They were denominated in barley or other crops and the interest rate was typically much higher than for commercial loans and could amount to 1/3 to 1/2 of the loan principal.