The Tughlaq Sultans who ruled India in 14th century, were from that part of Khurasan which is now western Afghanistan.
They belonged to the Qarauna/Negudari tribe of Mongols, spoke Mongolian, and were related to but distinct from Hazaras. Tughlaq was not the name of their tribe but the name of the founder of the dynasty who came from Khurasan to India according to Shams Siraj Afif (who served at Tughlaq court)  and his homeland was a mountainous region between Turkestan and Sind (according to Ibn-i-Batuta who was in service of Muhammad bin ughlaq for some years) i.e., the region of Ghor and hilly tract near Herat. 
They were part of the marauding Mongol armies in 13th century. According to Isami (author ‘Futh-us-Salantin; written in 1350s), Sultan Balban’s son was killed by a Qarauna horseman of the Mongol army in 1285 AD . In his elegy written at the death of Balban’s son Amir Khusrao has described his captor as a Qarauna :
“He sat on his horse like a leopard on a hill. His open mouth smelt like an armp-pit, whiskers fell from his chin like pubic hair. ” 
The Qaraunas appear to have been offspring of Mongol men and Indian women (captured from Punjab and Sind in their raids). Qara means black in Mongolian and Turki languages, and it is assumed that they had darker complexion. Marco Polo referred to them as ‘half-breeds’, and that Qarauna was another name for Negudari.
“Many towns and villages across this plain have tall, thick earthen ramparts to protect them against the bands of marauders known as Qaraunas who infest these parts. And why are they called Qaraunas, which means ‘mongrels’ in our language? When these people set out to rob and pillage the land, they cast diabolical spells that turn daylight to darkness until it is virtually impossible to see anything. And they spread this darkness over an area that takes seven days to cross. They know the lie of the land inside out, so when they have summoned the darkness they ride side by side – sometimes as many as 10,000 at once, sometimes more, sometimes less – and commandeer the plain they mean to rob so utterly that no one in their path can escape them and everything, man, beast and object, is liable to be seized. And when they have captured the men, they kill all the elderly and cart off the young to sell them as serfs and slaves. Their king is called Neguder. And this Neguder went with a good 10,000 of his own men to the court of Chagatai, a brother of the Great Khan, and stayed with him, because Chagatai was his uncle and a mighty lord.” 
Mughal king Babur in his description of Kabul (i.e. Kabulistan) wrote that Hazaras and Negudaris lived in the western mountains (to the west of Kabulistan) and some of them spoke Mongolian language at that time.
“On the west it (Kabul) has the mountain region in which are Karnud (?) and Ghor, now the refuge and dwelling places of the Hazara and Nikudari tribes.” 
“In the western mountains are the Hazara and Nikudari tribes some of whom speak the Mughuli tongue.”