How can a theory first appear in another discipline?

Suppose a sociologist develops a theory about how legal status affects labor mobility.

A historian later notices that the theory helps explain the transition from serfdom to wage labor.

The historian can then ask:

Does this theoretical mechanism fit the historical evidence?

If yes, the historian applies the theory to historical material.

How is it "rediscovered"?

Imagine:

Economist A develops an idea in 1920.

The idea is not widely noticed.

Decades later, historian B independently develops a similar explanation.

B discovers A's work—or reaches the same conclusion independently.

B then connects the idea to historical evidence.

We can call this 'rediscovery' in a loose sense.

I put quotation marks around "rediscovered" because it does not necessarily mean literally forgotten and then found again. It can mean that an idea is independently developed or later recognized as useful.