I think the myth that is the original article is referring to is probably your version of India dark ages story not the European dark ages story.

Believe it or not, Timur probably killed more muslim in his entire campaign than non Muslim.

The Delhi Sultanates created the Hindustan languages and started the Indo-Islamic architecture that reached its zenith during the Mughal Empire[1]. The Delhi Sultanate is also noted for its integration of the Indian subcontinent into a global cosmopolitan culture[2]. The Sultanate is a few forces in the world that has successfully repelled the Mongul catastrophic invasion. FYI, Mongul successfully decimated Baghdad of Abbasid empire and burnt it to the ground including the largest library known to the world at the time.

[1]https://en.m.wikipedia.org/wiki/Delhi_Sultanate

[2]Asher, C. B.; Talbot, C (1 January 2008), India Before Europe (1st ed.), Cambridge University Press, pp. 50–52, ISBN 978-0-521-51750-8