What specific ingredient arrival marked the divergence point between ancient flatbreads and modern pizza?

Answer

The tomato from the Americas

The evolution of the topped flatbread into recognizable pizza hinges entirely on the introduction and adoption of the tomato. This fruit arrived in Europe from the Americas centuries after the ancient Greek *plakous* was consumed and was initially met with suspicion, often being treated as ornamental or even poisonous around the 16th century. The critical shift occurred when the commoners of Naples started incorporating this ingredient into their flatbreads between the late 18th and early 19th centuries. This adoption created the essential cooked tomato sauce layer, which is indispensable to the modern culinary creation and definitively separates it from earlier, pre-Columbian topped breads.

What specific ingredient arrival marked the divergence point between ancient flatbreads and modern pizza?
inventionOriginItalianpizzaGreek