Shan Shen

Shan Shen was a planet inhabited by humans or a humanoid species with a Chinese culture. Some streets here were filled with flags, pagodas and various crowded stalls. Shan Shen's orbit neighboured several other celestial bodies, evidenced from the sight of nearby objects in from its upper atmosphere, one of which contained rings.

The Tenth Doctor once took Donna Noble to Shan Shen. She had her fortune read by a fortune teller working with the Trickster's Brigade.

After the Trickster's attempt to change history backfired, all of the writing on the planet — including that on the Doctor's TARDIS — changed into the phrase "Bad Wolf". This, coupled with the ominous tolling of the Cloister Bell, warned the Doctor that the end of the universe was approaching. (TV: Turn Left)

Behind the scenes
The name of the planet is given explicitly on screen by a female market stall merchant.

Shan Shen Shan Shen