Many 19th and 20th century writers noted that modern States grew out of families, tribes and clans. Modern historians seem to reject the notions of unidirectional social evolution. What is the current consensus on the reason for formation and development of State societies?
Can you please clarify what you mean by state. You say “modern state.” The modern state really gets cemented with the Treaty of Westphalia in 1648, where complex governments had been around for a long, long, long time.