Gurjara-Pratihara was a very long time ago, when kings ruled over big parts of India. The Gurjara-Pratiharas were one of those big groups of kings.
The Gurjaras lived in the northwestern part of India and were recognized for their bravery in warfare. Similarly, Pratiharas had the same qualities and hailed from the central part of India. The two groups combined to form the Gurjara-Pratihara Dynasty.
The dynasty was specifically prominent between the 6th and 10th centuries. They had a powerful army, which helped them conquer other kingdoms, but they were also great at trade and built big palaces and temples.
The Gurjara-Pratiharas were very tolerant of all religions, which meant that people of different faiths could live together in peace. They were also known for their big cultural and architectural contributions.
Eventually, the dynasty fell after a long time of being successful, but their legacy remained for future generations to learn from.