Social contract theorists like Hobbes, Locke and Rousseau were not in the first instance trying to give empirical accounts of how the state arose. They were attempting, rather, to understand a government's basis of legitimacy. But it is still worth thinking through whether the first states could have arisen through some form of explicit agreement among tribesmen to establish a centralised authority. Thomas Hobbes lays out the basic deal underlying the state: in return for giving up the right to do whatever one pleases, the state, or Leviathan, through its monopoly of force guarantees each citizen basic security.

The state can provide other kinds of public goods as well, like property rights, roads, currency, uniform weights and measures, and external defence, which citizens cannot obtain on their own. In return, citizens give the state the right to tax, conscript, and otherwise demand things of them. Tribal societies can provide only limited public goods because of their lack of centralised authority.

So if the state arose by a social contract, we would have to posit that at some point in history a tribal group decided voluntarily to delegate dictatorial powers to one individual to rule over them. The delegation would not be temporary, as in the election of a tribal chief, but permanent, to the king and all his descendants. And it would have to be on the basis of consensus on the part of all the tribal segments, each of which had the option of simply wandering off if it did not like the deal.

It seems highly unlikely that the first state arose out of an explicit social contract if the issue motivating it were simply economic, like the protection of property rights or the public goods. Tribal societies are egalitarian and close-knit kinship groups that value freedom. In contrast, states are coercive and hierarchical. This means the real driver of state formation is violence or the threat of violence.