No siege weaponry, so a double wide stone wall with timber internals was adequate. Each level would require a ladder breach. Very difficult. Height would allow archers and boiling implements, etc. Easy to secure. Towers close to one another offer interlocking fire.

Chinese have the same towers, used for centuries. Height of the tower was an indicator of families wealth. Food storage for protection from bugs/predators/thieves in upper levels.

Some of these towers have only recently fallen in to disuse in the old rurals of China.