Tejen is an oasis city located in the Karakum Desert within the Ahal Province of Turkmenistan. It is situated along the M37 highway, positioned between the towns of Duşak and Mary. The city lies approximately 223 kilometres (139 miles) southeast of the national capital, Ashgabat.
The city has a population of roughly 67,500 residents. It is located to the west of the larger oasis of Mary. Historically, some scholars suggest that Tejen may have served as the birthplace of Zoroaster.