Turkmenistan is among the least visited countries in the world, and that is largely by design. Ashgabat is built almost entirely in white marble, the Darvaza gas crater burns in the Karakum desert, and the ruins of Merv on the old Silk Road are the country's main historical site.
The guides here cover Turkmenistan as a whole. Independent travel is effectively not permitted: most visitors need a visa supported by a licensed operator and travel with a guide, while transit visas are limited and issued unpredictably. Photography is restricted around government buildings. Desert heat in summer is extreme, which leaves spring and autumn as the practical seasons.