A person with the surname Khan is a muslim in the Indian subcontinent. But Khan was originally a Mongolian surname like Genghis Khan. Since Mongolia is a predominantly Buddhist country, have anyone come across Buddhist Khans? How widespread is the usage of this surname. Since Mughal dynasty originated in Ferghana valley of Uzbekistan, is this a common surname in Northern Afghanistan and surrounding countries like Uzbekistan, Tajikistan etc ?
Another is the surname Shah. The first thing that comes to my mind when I think of Shah is Shah of Iran. I was under the assumption that Shah was of persian origin and was common surname in Iran and central Asia. But we have many hindus with last name of Shah and there is the now defunct Shah Dynasty of Nepal which is quite a distance removed from any persian influence. So how is that possible ?
and for the original question - khan is more a title in altaic languages, meaning leader or king. it isn't a name. when the mongol hordes swept thru central asia, the word got adopted in different parts as a title of respect. it is pretty much only in the indian subcontinent that it is used as a last name. pashtoon afghans don't use khan as last names, to them, every guy is called XYZ khan, as we use XYZ sahab.
in the indian subcontinent, khan, khan bahadur, rai, rai bahadur, were titles given by mughals to those loyal to them (khan for muslims, rai for hindus), and these were used as last names down the line.
Khan was considered a name for chieftains and later also adopted as a millitary term for junior field commanders. Khan was commander of 10,000 or a Tuman of troops and the only rank above that was Noyen (Prince) and Kha-Khan or KaGan which is literally "Great Khan" or Big Chief/king.
Bhadur is a word that means brave, many warriors that had proven track records in battle either as strategists or as individual fighters got the name Bahadur. As in Subedai Bahadur the Mongol General who was the right hand man of Ghengis and essentially his name means "Subedia the Valiant".
Mugals would often give this name to good generals or successful field troops and commanders. Bhadur means brave or valiant.
As for Rai I think its a senior rank among Hindus like chief or something... not too good on that one.
Shah is Persian for King. Shahensha was King of Kings or the big King "Emperor" to whom other kings served.
In Islam Sayeds are the decendants of the Prophet but also often rendered Shah...
I'm not sure how far back the Shah title goes personally I dont think its as old as some suggest... definately not Acheminid like Cyrus the Great and his decendants but probably something introduced from the times of Surena and the Parthians.
The reason why Pathans use both Khan and Shah for various chieftains is becuase they were influenced by the cultures that dominated them over these periods. Kabul was the un-official capital of Chagatai Khan. Many Mongols settled there and throughout Afghanistan... Likewise the Persians also dominated the region in the renaisace period and afterwards.