Turkmenistan (also Turkmenia) is a country in Central Asia.
You may get a visa at the Turkmen embassy in Dushanbe. Easiest way is to ask for transit visa. You need to show visa of country you going to visit via Turkmenistan (Kazakhstan, Iran, Uzbekistan or Azerbaijan). Points and dates of entry and leaving are fixed. Also a transit visa is limited in 5 days.
All border controls operate from 08:00 to 17:00.