You can at first check Mongolia section and Yuan section in the book list of this subreddit.

I can also recommend some of the new works on the formation of the Mongol Empire:

• Jackson, Peter. The Mongols and the Islamic World from Conquest to Conversion. New Haven: Yale UP, 2017.
• May, Timothy. The Mongol Empire. Edinburgh: Edinburgh UP, 2018. The Edinburgh History of the Islamic Empires.

While May's is more readable textbook formats and give an excellent overview in schematically arranged composition, Jackson provides us with dense description, including the introduction to primary texts. May also authors several, more concise introductory works on the Mongols, such as: May, Timothy. The Mongols. Leeds: Arc Humanities Press, 2019. Accessed March 19, 2021. http://www.jstor.org/stable/j.ctvmd838h.

Rossabi, Morris. The Mongols: A Very Short Introduction. Oxford: OUP, 2013 is also an excellently written introduction, including their cultural history (though it might be a too lengthy for the total beginner of the topic).

(Edited): Corrects the format of the mentioned references.