鞍上人なく鞍下馬なし
あんじょうひとなくあんかうまなし
riding a horse so skillfully that it appears as if man and horse have become one
鞍馬 is read as あんば (amba) and means saddled horse.
あんば
amba
あんじょうひとなくあんかうまなし
riding a horse so skillfully that it appears as if man and horse have become one