Archeology CAN NOT give a clear and accurate picture of historical events just like materialistic modern science CAN NOT explain the infinite and highly complex world of 31 realms. It is only possible to know by higher wisdom (Abhinna) which comes through purification of mind.
The historical accounts given in the Mahavamsa are mostly inaccurate. The Jaya Sri Maha Bodhi is NOT a twig-branch of Bodhi Tree in India. Its actually the opposite.
The Jaya Sri Maha Bodhi in Anuradhapura IS THE REAL BODHI TREE. The Bodhisattva attained Samma Sambodhi sitting here only.
The real Bodhi Tree CAN NOT be destroyed by anything or anyone in the universe because it is the focal point of the Pure Immeasurable Buddha Energy.
I am not the right person to discuss this. But there is a time coming in the near future when Sri Lanka will be full of Arahants and the Buddha Sasana will shine brightly once again ! (There are beings with higher Paramitas for this purpose like our most Ven. Waharaka Thero). The world will witness great Arahants with six higher knowledge (including supernatural powers). The Real picture will become clear by then !
May all beings develop unshakable faith in Supreme Buddha-Dhamma-Sangha and achieve the Supreme bliss of Nibbana !!!