To enter Turkmenistan all travelers are required to have a transit or tourist visa. The tourist visas are delivered on the basis of an issued visa support letter, also referred to as a Letter of Invitation. The LOI requires usually 7-10 working days to process.
With an approved LOI you can apply for your visa at a Turkmen embassy or consulate abroad, or obtain it directly at the Turkmen land border at Gaudan (Bajgiran/Mashad, Iran), Farab (Bukhara, Uzbekistan), Dashoguz (Shavat\Khiva, Uzbekistan), Kunya-Urgench (Khojeyli\Nukus, Uzbekistan); at the sea port in Turkmenbashi, or at the international airport in Ashgabat upon arrival.
The last decision about result of the letter of invitation depends on the Turkmenistan Migration Department;