There are three main aspects of the decline of Śaiva siddhānta tāntrika systems and confining it to mainly the Tamil lands
- Loss of patronage in the North due to Muslim invasions+active iconoclasm by them.The last rulers who could do this(patronage) to some extent in the North would be the family in which Rani Durgavati married in.
- When Vijayanagara came to power,it elevated the Telugu smārta-s and disenfranchised the Ādiśaivas(replacing them with Telugu brāhmaṇas).
- After the very brief revival it enjoyed due to people like Arumuga Navalar,it became a tool in the hands of Dravidianist ideologues who distorted it out of it contexts.
However,the works of Sekkizhar,and the works of Sundarar and Nambiyandar Nambi ensured that the system survived in the popular devotional consciousness in those lands even after their patronage declined.