For general background, I recommend:”A Thousand Years of the Tartars”, by E. H. Parker;”The Empire of the Steppes”, by Rene Grousset,tr. Naomi Walford; “The Barbarians of Asia”, by Stuart Legg.
For the Mongols, in general:”The Encyclopedia of Mongolia and the Mongol Empire”, by Christopher P. Atwood; “Historical Dictionary of the Mongol World Empire”, by Paul D. Buell; “History of the Mongols”, by Bertold Spuler; “The Mongols”, by David Morgan; “The Mongols: A History”, by Jeremiah Curtin; “The History of the Mongol Conquests”, by J.J. Saunders; “The Mongols” [Osprey Mn at Arms Series]; “The Mongol Art of War”, by Timothy May”Mongol Warrior: 1200-1350 [Osprey Warrior Series]; “Storm from the East” Robert Marshall.by
For Chinnghis Quan: “Genghis Khan and the Making of the Modern World”, by Jack Weatherford; “Genghis Khan: His Life and Legacy”, by Paul Ratchnevsky; “Genghis Khan”, by R.P. Lister; “National Geographic”,Vol. 190, No. 6, Dec. 1996
For the Great Khans:”The Mongol Warlords”, by David Nicolle; “National Geographic”, Vol. 191, No. 2, February, 1997; Khubilai Khan: His Life and Times”, by Morris Rossabi
The Mongols and the West:”The Devil's Horsemen, supra; “The Mongols and the West”, by Peter Jackson; “Kalka River 1223” [Osprey Campaign]”Russia and the Golden Horde”, by Charles J. Halperin; “Mongols and Mamluks”, by Reuven Amitai-Preiss.
Miscellaneous: “Genghis Khan's Greatest General: Subotai the Valiant”, by Richard A. Gabriel; “Qaidu and the Rise of the Independent Mongol State in Central Asia”, by Michael Biran”The Tartar Khan's Englishman”, by Gabriel Ronay
You are a Mongol scholar. That’s an incredible list. I’m always intrigued by the peoples of arid and desert regions. They are natural nomads. And nomads always end up raiding the settled agricultural people because they need the vegetables fruits grains food they raise. Because nomadism can only provide an incomplete diet
They could trade with agricultural people but it is easier to raid them and more fun. Warrior kind of fun and rape and pillage