A societal order based on land ownership developed that was known as

Feudalism

Explanation:

The system defining hierarchical system based on land ownership, protection & mutual obligation : is called as Feudalism.

It emerged in ancient history of Europe.

It consists of nobility class (land owners), known as 'lords'. They recompense knights, vessels & serfs - by granting them piece of land (called fiefdoms) return of which the latter fight for the former.