At the break of dawn, the fertile plain of Mrauk U, on a remote river in western Myanmar (Burma), is an archaeologist's dream come true.

The sun washes over hundreds of medieval temples, pagodas, and palaces. This is the lost capital of a fabled empire. Here the powerful kings of Arakan commanded the trade routes of South Asia from a city of 20 square miles (52 square kilometers) and 160,000 inhabitants. Today plowmen silently guide their water buffalo through verdant rice paddies, and cows wander the grounds of 600-year-old monasteries. (Read about the race to save architecture in Myanmar's biggest city.)

But the dreamlike calm of Mrauk U cloaks a 21st-century nightmare. Myanmar's Rakhine region, where the ancient city lies, is