Sandwiched between the vast desert emptiness of the Dasht-e Kavir and the steppes of Central Asia, northeastern Iran has a spine of mountains that become more lushly forested as you head west. East of Minudasht the wilderness has been declared the Golestan (Paradise) National Park. Above the overdeveloped Caspian coast rise more forests and the grand Alborz Mountains.
Mashhad's extraordinarily grand Haram-e Razavi complex surrounding the tomb of Imam Reza is Iran's holiest site and draws millions of pilgrims each year. Mashhad is also the logical staging point for visiting Afghanistan or Turkmenistan.
Spring (March to May) is the most beautiful season and visitors catch the steppe and mountains mantled in glorious technicolour flowers. But beware, Mashhad is engulfed by No Ruz (Iranian New Year) holidaymaking hordes (late March) and pilgrims for religious festivals such as Ramadan, and ends up transformed into Dante's hell.
April to June means you will miss the worst human scrums, still get to enjoy masses of late-blooming flowers in the mountains and dodge the worst of the summer humidity, for which the Caspian coastline is infamous.
Historically, the area developed as Khorasan (Where the [Iranian] Sun Rises) and Tabarestan/Mazandaran (the southeastern Caspian littoral). Millennia of culture reached a zenith here around 1000 years ago, producing many of the era's great scientists and poet-philosophers. But the XIII and XIV century ravages of the Mongols and Tamerlane were so complete that Tabarestan's settled civilisation was virtually wiped out. Even now the sites of several once-prosperous cities are mere undulations in the steppe. A few marvellous, lonely towers, most astonishingly at Radkan and Gonbad-e Kavus, are the last witnesses of former glories.
The XVI century Safavid regime's move towards formal state Shiism was a major factor in the growth of Mashhad from a shrine-village to the region's foremost city.