Overview
There are several ways to go from Europe to South Asia overland.
All require some caution. Roads are poor in many areas and some are impassable in winter or in monsoon season. Various mountain and desert areas can be quite dangerous if appropriate care is not taken. So can some of the inhabitants. Most are friendly, curious and helpful, but the traveler needs some understanding of local customs and must take some care not to give offense.
Options
The Silk Road
Istanbul to New Delhi over land: Turkey - Iran - (Afghanistan) - Pakistan - India
Alternatively: Turkey - Georgia - Azerbaijan - Turkmenistan - Uzbekistan - Kyrgyzstan - China - Pakistan - India
Alternatively: Turkey - Georgia - Armenia - Iran - (Afghanistan) - Pakistan - India
See also Silk Road
Through Russia
There are many ways to go to South Asia through Russia, but since traveling in Afghanistan is hardly possible you'll have to go through Iran or China. That gives the following options:
Russia to Iran
Through the Caucasus, then following the Silk Road
Via Central Asia
Russia to South Asia via China
From Russia to Central Asia, then into China in one of these ways:
* Northwest China, road or rail from Almaty, Kazakhstan to Urumqi. See Moscow to Urumqi for details.
* It may be possible to cross China's Western border further South, following the Silk Road toward Kashgar. This would involve some roads that have seen very few tourists.
* From the North, road or Trans-Siberian Railway to Ulan Ude, into Mongolia to Ulaanbaatar and on into China
* Trans-Siberian Railway all the way to Beijing
* From the Northeast (if you want to visit Eastern Russia), Southwest from Vladivostok to Harbin
From China, there are several routes toward South Asia
* In the West, from Kashi, South over the Karakoram Highway into Pakistan
* In the center, through Tibet to Kathmandu
* in the Southwest, from Kunming into Myanmar, but visas for this may be difficult
* in the South, from Nanning into Vietnam