This discussion explores a radical historical thesis asserting that the geographic core of ancient Buddhism was not the Indian subcontinent, but rather the island of Sri Lanka. The source argues that 19th-century colonial archaeologists, led by Sir Alexander Cunningham, mistakenly mapped the "Middle Kingdom" described by Chinese monk Faxian to Northern India to serve the political prestige of the British Empire. By forensicly re-evaluating Faxian’s travel logs, the text demonstrates that the scale of ruins and precise geographic measurements—such as the distance between the royal capital and the sacred mountain footprint—align perfectly with the Sri Lankan landscape rather than the Indian plains. Ultimately, the narrative challenges the linguistic interpretation of "Deepa" as a continent and posits that the true Jambudvipa was a federation of lands within Sri Lanka, suggesting the world has fundamentally misplaced the cradle of Buddhist civilization for over 150 years.