former post; previous station
Refers to the place or position where someone was previously assigned, especially in work contexts like diplomatic, military, or corporate transfers.
He applied the experience he gained at his former post to the new project.
My previous station was Singapore.
赴任地 is the place to which one is newly assigned, whereas 前任地 is the place one has left.
Compound of 前 (zen, 'previous') + 任 (nin, 'duty/assignment') + 地 (chi, 'place').