Why was Italy an ideal location for cultural changes after the Middle Ages?

In the 13th century, much of Europe experienced strong economic growth. The trade routes of the Italian states linked with those of established Mediterranean ports, and eventually the Hanseatic League of the Baltic and northern regions of Europe, to create a network economy in Europe for the first time since the 4th century. The city-states of Italy expanded greatly during this period, and grew in power to become de facto fully independent of the Holy Roman Empire; apart from the Kingdom of Naples, outside powers kept their armies out of Italy. During this period, the modern commercial infrastructure developed, with double-entry bookkeeping, joint stock companies, an international banking system, a systematized foreign exchange market, insurance, and government debt. Florence became the center of this financial industry, and the gold florin became the main currency of international trade.