Periodically "clean slate" decrees were signed by rulers which cancelled all the rural (but not commercial) debt and allowed bondservants to return to their homes. Customarily rulers did it at the beginning of the first full year of their reign, but they could also be proclaimed at times of military conflict or crop failure. The first known ones were made by Enmetena and Urukagina of Lagash in 2400-2350 BC. According to Hudson, the purpose of these decrees was to prevent debts mounting to a degree that they threatened fighting force which could happen if peasants lost the subsistence land or became bondservants due to the inability to repay the debt.
What was it called when rulers cleared commercial debts?