Overland travel or overlanding refers to an "overland journey" - perhaps originating with Marco Polo's first overland expedition in the 13th century from Venice to the Chinese court of Kublai Khan<1>http://www.bbc.co.uk/dna/h2g2/A566453<1>. Today overlanding is a form of extended adventure holiday, embarking on a long journey, often in a group. Overland companies provides a bus and a tour leader, and the group travels together overland for a period of weeks or months.
Since the 1960s overlanding has been a popular means of travel between destinations across Africa, Europe, Asia (particularly India), the Americas and Australia. The "Hippie Trail" of the 60s and 70s saw thousands of young westerners travelling through the Middle East to India and Nepal.
At 9,288km the Trans-Siberian Railway is one of the longest overland journeys in existence today, taking 7 days to reach Vladivostok from Moscow, and providing an alternative to air travel for journeys between Europe and Asia.
The introduction of Japan's high speed railway Tōkaidō Shinkansen in 1964 changed to face of rail travel. The railway has carried more than 4 billion passengers and its new N700 series trains are capable of 300km/hr. France's TGV holds the record for the fastest train, with a top speed of more than 500km/hr, making it faster than air travel for many journeys within the country.
The Silk Route or Silk Road historically connects the Mediterranean with Persia and China. Today the route refers to overland journeys between Europe and China, taking either the northern route - through Russia and Kazakhstan - or the southern route - through Turkey, Iran, Pakistan and North India - to Urumqi or Xian in China. These routes are still popular today, with companies such as Oasis Overland [] and Odyssey Overland [] offering tours on the southern route. More recently groups such as BuddhaBus [] have provided an express service along the northern route, as security issues in Afghanistan and Pakistan have made travel more difficult.
One of the most common - and longest - overland expeditions is in Africa, connecting Cairo in Egypt with Cape Town in South Africa. The route covers more than 10,000km and usually takes in Sudan, Kenya, Tanzania, Zimbabwe and Namibia along the way. Overland operators in these areas include Dragoman [].
Since 2006 a few companies have offered overland expeditions from the UK to Australia. Originated by Exploratory Overland Expeditions  in 2006, the expedition is marketed as the longest overland journey available.