It was important for them to be able to stop the muslim armies from advancing farther into western europe.
During the period of the Renaissance, Italy was divided into numerous small city-states controlled by local wealthy people. There were large differences though from one city-state to another, and while the northern ones were very wealthy and had things going very smoothly, the southern ones were much less successful.
The reason why the northern Italian city-states were so wealthy was mostly the trade. These city-states had excellent large ports. They were producing multiple things that were in high demand and also very well paid for for export, and were getting lot of things they needed and desired from the other parts of the world.
These states had very well developed fleets, and they were trading with multiple Asian regions, Europe, as well as parts of Africa. They were exporting their high quality products. Very often they were buying certain things from one place, then re-sell it in other place buy much higher prices, thus getting more and more wealth over time. That wealth enabled them to get all they needed without any problem, thus making them very stable and strong small states.
