Why did the crusaders kingdoms depend on Italian port cities like Venice and Pisa for supplies?

The Crusader kingdoms relied on Italian port cities like Venice and Pisa for supplies due to their strategic locations and established maritime trade networks. These cities had the necessary ships, expertise, and resources to transport goods, weapons, and reinforcements across the Mediterranean. Additionally, the Italian city-states sought to expand their commercial interests and influence in the region, creating a mutually beneficial relationship with the Crusaders. This dependency was crucial for the sustenance and military success of the Crusader states in the Holy Land.