Tejen is an oasis city in the Karakum Desert, in Ahal Province of Turkmenistan. It lies along the M37 highway, between Duşak and Mary, 223 kilometres (139 mi) by road southeast of Ashgabat. It has a population of approximately 67,500. To the east is the larger oasis of Mary. Khlopin suggests Tejen may have been the birthplace of Zoroaster.