Peter I the Great (1672–1725) played a major role in introducing Russia to the European state system. While the vast land had a population of 14 million, grain yields trailed behind those of agriculture in the West, compelling nearly the entire population to farm. Only a small percentage lived in towns. The class of kholops, close in status to slavery, remained a major institution in Russia until 1723, when Peter converted household kholops into house serfs, thus including them in poll taxation. Russian agricultural kholops were formally converted into serfs earlier in 1679.