While Machiavelli was penning his masterpiece, several rulers through Europe are already beginning to practice many of his ideas. These rulers agreed with Machiavelli that effective sovereignty necessitated total centralization of power.
In France under Louis XI, the power of dukes was finally broken in 1472 and the road to the modern state was paved. In Spain, Ferdinand and Isabella did the same. They drove out the Muslims and Jews and instituted the inquisition to root out all dissenters. In England, King Henry the VIII continued the centralization of power begin by his father. He dominated the other nobles and the parliament. He also increased his power by putting the Anglican church fully under his influence and separating from Rome in 1534.
As Machiavelli gathered from his study, the centralization of power was the key. On fact, he wrote the prince as manual for Lorenzo de Medici to do the same in Italy.
By the time Thomas Hobbes came into the scene in the early 1600s, the modern state had become well instituted in many places over a 100 years. Hobbes sought to provide a new explanation and justification for it that went deeper than raw power.