As primitive social systems gradually disintegrated, society became increasingly stratified into distinct classes. Owing to the low level of productive forces at the time, commoners—or freemen—lived at a subsistence level, unable to produce the surplus necessary for societal development. As a result, slaves emerged as the principal labor force responsible for the creation of surplus value, and they remained the dominant producers over an extended period. This was largely because slave owners were under no obligation to account for the needs of the enslaved, thereby enabling the extraction of uncompensated labor. Slave society thus marked the first historical stage with a socioeconomic system based on exploitation.