could not live on these lands since they were comparably small. Below the free men were the unfree men (šiluhlu̮). The unfree men had given up their freedom and entered the services of others on their own accord, and were in turn provided with clothes and rations. Many of them probably originated as foreigners. Though similar to slavery, it was possible for an unfree person to regain their freedom by providing a replacement and they were during their service considered the property of the government rather than their employers. Other lower classes of the Middle Assyrian period included the ālāyû ("village residents"), ālik ilke (people recruited through the ilku system) and the hupšu, though what these designations meant in terms of social standing and living standards is not known. The Middle Assyrian structure of society by and large endured through the subsequent Neo-Assyrian period. Below the higher classes of Neo-Assyrian society were free citizens, semi-free laborers and slaves. It was possible through steady service to the Assyrian state bureaucracy for a family to move up the social ladder; in some cases stellar work conducted by a single individual enhanced the status of their family for generations to come. In many cases, Assyrian family groups, or "clans", formed large population groups within the empire referred to as tribes. Such tribes lived together in villages and other settlements near or adjacent to their agricultural lands. Slavery was an intrinsic part of nearly every society in the ancient Near East. There were two main types of slaves in ancient Assyria: chattel slaves, primarily foreigners who were kidnapped or who were spoils of war, and debt slaves, formerly free men and women who had been unable to pay off their debts. In some cases, Assyrian children were seized by authorities due to the debts of their parents and sold off into slavery when their parents were unable to pay. Children born to slave women automatically became slaves themselves, unless some other arrangement had been agreed to. Though Old Babylonian texts frequently mention the geographical and ethnic origin of slaves, there is only a single known such reference in Old Assyrian texts (whereas there are many describing slaves in a general sense), a slave girl explicitly being referred to as Subaraean, indicating that ethnicity was not seen as very important in terms of slavery. The surviving evidence suggests that the number of slaves in Assyria