Complex sentence: Alauddin Hussain Shah (reign 1494-1519) the founder of the Husain Shahi dynasty, occupied the throne of Bengal by assassinating the Habshi Sultan Shamsuddin Muzaffar Shah, under whom he had served as "wazir".
Split into simpler sentences: Alauddin Hussain Shah (reign 1494-1519) was Sultan of Bengal who had founded the Hussain-Shahi dynasty. He became the ruler by assassinating the Habshi Sultan Shamsuddin Muzaffar Shah, under whom he had served as the "wazir".