Ron "Modar" Knight suggest you to read these books

The Secret History of the Mongols, Translated by Francis Woodman Cleaves, Harvard University Press, 1982.
ISBN: 0-674-79670-5 The Secret History of the Mongols is the most important Mongolian source of events of
the Empire period. As such, it is unique and must be regarded as authoritative historical evidence.

Genghis Khan - His Life and Legacy, by Paul Ratchnevsky, Blackwell Press, 1992. ISBN: 0-631-16785-4
This is considered the most scholarly authoritative among the biographies of the Great Mongol.

Altan Tobci, A Brief History of the Mongols, Translated by C. Bawden, Otto Harrassowitz, Wiesbaden, 1955.

Barthold, W. : Turkestan Down to the Mongol Invasion, Luzac & Company Ltd, London 1977.

Blunt, Wilfrid: The Golden Road to Samarkand, Viking Press, New York, 1973.

Boyle, J.A. (edited by): The Cambridge History of Iran, Volume 5, "The Saljuq and Mongol periods."
Cambridge University Press, 1968.

Brent, Peter: Genghis Khan, McGraw Hill, New York, 1976.

Burks, R. V. : Some Elements of East European History, Pub. 38, American History Assn., Washington, 1961.

Chambers, James: The Devil's Horsemen, Atheneum, New York, 1979.

Christian, David: A History of Russia, Central Asia and Mongolia, Blackwell Publishers Ltd. 1998.

Dawson, Christopher (edited by): The Mongol Mission, The Makers of Christendom Series, Sheed and Ward,
New York, 1955.

de Hartog, Leo: Genghis Khan, Conqueror of the World, I. B. Tauris & Co. Ltd, 1979.

de Hartog, Leo: Russia and the Mongol Yoke, British Academic Press, 1996.

Grousset, Rene: Conqueror of the World, translated from French by M. McKellar and D. Sinor, Orion Press,
New York, 1966.

Grousset, Rene: The Empire of the Steppes, Rutgers University Press, 1970.

Halperin, Charles J. : Russia and the Golden Horde, I. B. Tauris 1987.

Heissig, Walther: The Religions of Mongolia, University of California Press, 1980.

Henning Haslund-Christensen (collected by) : The Music of the Mongols, Da Capo Press, New York 1971.

Hoang, Michel: Genghis Khan, Saqi Books, 1990.

Humble, Richard: Marco Polo, G. P. Putnam's Sons, New York, 1975.

Jagchid, Sechen, and Hyer, Paul: Mongolia's Culture and Society, Westview Press, Inc. 1979.

Juvaini, `Ala-ad-Din: The History of the World Conqueror, translated from the text of M. Qazvini by John A. Boyle,
Vol. 2, Harvard Univ. Press, Cambridge, Mass., 1958.

Koch, H. W. : Medieval Warfare, Bison Books Ltd., London, 1978.

Komroff, Manuel, ed. : Contemporaries of Marco Polo, Dorset Press

Lamb, Harold: Genghis Khan, The Emperor of All Men, McBride and Co., 1927.

Lattimore, Owen: Chingis Khan and the Mongol Conquests, Scientific American nr. 209, August 1963.

Liddell Hart, B. H. : Great Captains Unveiled -- Chapter 1: "Jenghiz Khan and Sabotai", Ayer Co., Pub., Inc.,
Salem, N. H., 1928. Reprinted 1984.

Lister, R. P. : Genghis Khan, Dorset Press, New York, 1969.

Mackenzie, Donald A. : China and Japan, Myth and Legands, Senate Press, London 1994.

Martin, H. Desmond : The Rise of Chingis Khan and His Conquest of North China, Johns Hopkins Press,
Baltimore, 1950.

Morgan, David: The Mongols, Blackwell Press, 1986.

Onon, Urgunge: The History and Life of Chinggis Khan, E.J. Brill Publ., 1990.

Pao, Kuo-Yi: Studies On The Secret History of the Mongols, Uralic and Altaic Series, Vol. 58, Indiana Univ. Pub.
Bloomington, Ind., 1965.

Riasanovsky, Valentin A. : Fundamental Principles of Mongol Law, Indiana Univ. Pub., Uralic and Altaic Series,
Vol. 43, Bloomington, Ind., 1965.

Ronay, Gabriel: The Tartar Khan's Englishman, Cassell, London, 1978.

Saunders, John J. : The History of the Mongol Conquests, Barnes and Noble, New York, 1971.

Sinor, Denis (edited by): The Cambridge History of Early Inner Asia, Cambridge University Press, 1990.

Spuler, Bertold: History of the Mongols, Dorset press, 1968.

Trubetzkoy, Nikolaj Sergeevich: The Legacy of Genghis Khan, Michigan Slavic Publications, Ann Arbor 1991.

Vernadsky, George: The Mongols and Russia, Yale University Press, 1953.

Vernadsky, George: "The Scope and Content of Chingis Khan's Yasa." Printed in Harvard Journal of Asiatic Studies,
Volume 3, 1938, pages 337-360.

Vladimirtsov, B. Ya. : The Life of Chingis-Khan, translated from the Russian by Prince D. S. Mirsky, Benjamin Blom,
New York, London, 1930.

Wheeler, G. (translated by): The Mongols In History, Praeger Pub., New York, Washington and London, 1971.

Williams, Brian: Genghis Khan, Rourke Pub. Co., Windermere, Florida, 1979.

Yip, Jacky, and Bonavia, Judy: The Silk Road, Chartwell Books, Inc., Secaucus, N. J., 1988.

A History of Asia, Vol. 1, W. Bingham, H. Conroy, F. Ikle, Allyn and Bacon, Inc., Boston, 1964.

Tamerlane, Garden City Pub. Co., Garden City, New York, 1928.

The March of the Barbarians, Literary Guild of America, Garden City, New York, 1940.

Storm Across Asia (Genghis Khan and the Mongols, and The Mogul Expansion), HBJ Press, New York, 1980.

Warfare in the Middle Ages, The Mallard Press, 1989.