Merv is the old­est and best-pre­served of the oasis-cities along the Silk Route in Cen­tral Asia. The remains in this vast oasis span 4,000 years of human his­to­ry. A num­ber of mon­u­ments are still vis­i­ble, par­tic­u­lar­ly from the last two mil­len­nia.