really, if u r really 'sonali' and not a 'M' hiding under 'H' name then tell me 1. who attacked jerusalem ,Persia egypt ? It was Umar al-khattib,a arab and prophet mohammads trusted liuetnant.
2.and who attacked India ? it was mohammad bin qasim, a arab.and who where mohammad ghazni, ghori , khilji? were they mongols?
mongols came much later in 13th , 14th century, arabs were invading much before that since 7th century. arabs viewed mongols as competitors in conquests.