Excerpts from Books and Wikipedia
"In 962 a Turkic governor of the Samanids, Alptigin, conquered Ghazna (in present-day Afghanistan) and established a dynasty, the Ghaznavids, that lasted to 1186. The Ghaznavid empire grew by taking all of the Samanid territories south of the Amu Darya in the last decade of the 10th century, and eventually occupied much of present-day Iran, Afghanistan, Pakistan and northwest India. The Ghaznavids are generally credited with launching Islam into Hindu-dominated India. The invasion of India was undertaken in 1000 by the Ghaznavid ruler, Mahmud, and continued for several years. They were unable to hold power for long, however, particularly after the death of Mahmud in 1030. By 1040 the Seljuqs had taken over the Ghaznavid lands in Iran." [Wikipedia]