What economic and political causes led to the rise of the italian city states

Some important causes here included the fact that italian city states duing the renaissance age were somewhat politically self-sufficient. All of them had powerful families that had rule over the cities. Furthermore, all of them, or the majority at least, had established trade with other cities as well as built navies that supplied them with goods from other lands. All of this enabled them a high level of autonomy and political power.