“Engulfed in complete darkness, the scholars made a beginning in the direction of locating Kapilavastu like a wild-goose chase,” K. M. Srivastava, of the Archaeological Survey of India, wrote in a memoir of his expedition to the Indian town of Piprahwa.

His discoveries, he wrote, a bit huffily, so infuriated a “particular set of scholars” that they “derived pleasure in indulging in the most unparliamentary language” questioning the identity of Kapilavastu.

The Indian consensus has held — at least in India, where tour operators market Piprahwa as “the place where the Buddha spent his childhood grappling with the overwhelming and puzzling problem of human existence.” This spring, India’s minister of culture opened a museum there, displaying evidence, mostly in the form of inscriptions on ancient seals, that was said to prove it was the true site of the Buddha’s childhood home.

Image A Unesco-backed team cut down through brick structures in Tilaurakot, Nepal, last year and discovered a second fortification with ramparts made of clay. Credit... Hari Thapi/Unesco

Across the border in Tilaurakot, a Nepali-British team supported by Unesco has been plowing ahead with its own hypothesis: that an Indian-organized expedition in the late 1960s had simply stopped digging too early.

The leader of that Indian expedition, Debala Mitra, uncovered traces of a sprawling brick city, but she said it could not have been Kapilavastu because it had been built hundreds of years after the Buddha’s life. Last year, the Unesco-backed team cut down through the brick structures Ms. Mitra had found and discovered a second fortification whose ramparts were made of clay.

Then they dug even farther, slowing their work to a crawl. They were watching for cylindrical depressions in the earth: evidence that under the clay fort had once stood timber fence posts, perhaps for so long that the wood had decayed, leaving a shell of earth behind.