What caused the growth of cities in Europe during the Middle Ages? How did new cities appear?

The growth of cities was caused by the development of trade and the emergence of new trade routes, for example, “from the Varangians to the Greeks” (through the territory of Russia), as well as the general growth of the economy, an increase in productivity and the transition from slash-and-burn agriculture to more productive forms. The growth of cities was facilitated by the separation of handicrafts from agriculture.

The raids of the Hungarians, Vikings and Arabs stopped, this also contributed to the growth of cities.

Cities arose in the following ways:

At the crossroads of trade routes (Volokolamsk in Russia, for example).
In place of castles or at their walls.
Near bridges or fords across rivers.
It could have just been founded by some prince (Moscow, Dmitrov, Kostroma, Vladimir, Yuryev-Polsky)