en_tn/gen/14/04.md

400 B

Twelve years they had served

The events in verses 4-7 happened before verse 3. Your language may have a way of showing this.

they had served Kedorlaomer

They probably had to pay him taxes and serve in his army. AT: "they had been under the control of Kedorlaomer" (See: rc://en/ta/man/translate/translate-names)

they rebelled

"they refused to serve him" or "they stopped serving him"