Complex sentence: Though it is not clear as why such an immortal place of worship lost glory but some historians cite it to Hyder Ali of Mysore Sultanate destroyed the temple, plundered the temple wealth during his invasion of Chittoor district, as part of expansion of his kingdom.
Split into simpler sentences: Though it is unclear as why such an important place of worship lost its glory, some historians cite Hyder Ali of Mysore Sultanate as the destroyer of the temple. He plundered the temple wealth during his invasion of Chittoor district, as part of expansion of his kingdom.