The Gurjara Pratiharas declined due to dynastic strife. The final blow came in the form of a raid by Indra III of the Rashtrakutas that devastated the Gurjara Pratihara capital of Kannauj.
For further reading check the following articles:
|100 Differences Between Articles||UPSC Prelims|
|NCERT Medieval Indian History Notes UPSC||UPSC Mains Questions (2013-2019)|
|NCERT Ancient Indian History Notes UPSC||NCERT Modern Indian History Notes UPSC|