The area now known as Happy Valley was formerly known as Wong Nai Chung Valley, sometimes known as Wong Nai Chung Kuk () or Wong Nai Chung Valley because of the Wong Nai Chung (, "lit." yellow mud stream) that leads into the area, where the Wong Nai Chung referred to is a mud-filled river collecting waters from the Wong Nai Chung Gap and surrounding area. The river nourished the rice paddies until the construction of Happy Valley Racecourse in 1846.