Khorasan is a region in the north-east of Iran. Previously a single province, it was split into three in 2004.
In middle Persian, Khorasan literally meant "where the sun rises"—a fitting name as this region at the northeastern tip of Iran is where the sun is seen earliest in the country every day. Apart from the hard-to-miss holy city of Mashhad, here you will find ancient buildings and artifacts from various empires that ruled the region throughout the history intermingling with a diverse array of ethnicities (Turkmens, Afghans/Pashtuns, Baluchis, and Arabs depending on where you are).
Whether you are on an overland tour of the world west to east, or are following the steps of Marco Polo along the Silk Road, Khorasan can be a great gateway to Central Asia. In addition to the transportation links to West Afghanistan and Turkmenistan the region has, and the consulates of Central Asian countries conveniently based in Mashhad, traditional yurts of nomadic Turkmens dotting the Khorasani countryside (especially on its northern reaches) will make you feel you are at the gate of something different from now-familiar Persian heartland.