In the autumn, flowers from orchards upriver from Huế fall into the water, giving the river a perfume-like aroma, hence the sobriquet.

[1] The Hương River has two sources; both begin in the Dãy Trường Sơn mountain range and meet at Bằng Lãng Fork.

The river continues, passing Hen islet and various villages, crossing the Sinh junction (capital of ancient Châu Hóa) before emptying into the Tam Giang lagoon.

After observing that Bang Son resembled a screen, the Nguyễn dynasty decided to build up Huế, which became known as their "Forbidden Purple City".

Emperor Gia Long approved the design of geomancers, which chose this mount as a front altar of the imposing and solid defending wall system, and renamed it Ngự Bình.