noun
beside a nobleman; close aide
Historical term for being in the immediate presence or service of a high-ranking person such as a shogun or lord. Also refers to a trusted attendant.
彼は将軍のお膝元に仕える側近だった。
He was a close aide serving at the shogun's side.
江戸は徳川将軍のお膝元として栄えた。
Edo flourished as the seat of the Tokugawa shogun.
noun
one's home turf; one's own backyard
Modern extended use: a place where a person or group has strong influence or feels at home. Often used in political, business, or local contexts.
地元の選挙区は彼のお膝元だ。
His home constituency is his own turf.
あの店は社長のお膝元で、いつも特別扱いだ。
That shop is the company president's home ground and always gets special treatment.
地元 is a general term for one's hometown or local area, while お膝元 implies a sphere of influence or a place under someone's direct control, often with a historical or hierarchical nuance.
本拠地 means 'base of operations' or 'headquarters' and is more neutral and modern, whereas お膝元 carries a traditional, often feudal, connotation of a ruler's seat.
From お (honorific prefix) + 膝元 (area around the knees), literally 'at the knees' of a superior. Originally referred to being in close attendance to a noble, later extended to the place where a ruler resides and, by further extension, one's sphere of influence.