As per NPR, archeologists have found the ruins of a ancient Cambodian city using remote-sensing technology.

Mahendraparvata, a 1,200-year-old lost city that predates Cambodia’s famous Angkor Wat temple complex by 350 years, was part of the Hindu-Buddhist Khmer Empire that ruled much of Southeast Asia from about 800 to 1400 A.D.

From Wikipedia, the location is in deep, swampy jungle — perfect for the ’30s (or even modern — added danger: landmine are common there) pulp-style game:

They initially uncovered five new temples. Eventually, using the Lidar data, 30 previously unidentified temples were discovered. In addition to the temples, their research showed the existence of an elaborate grid-like network of roads, dykes and ponds forming the city…The city’s origins date to the reign of Jayavarman II, considered founder of the Khmer Empire. His reign was consecrated on the sacred mountain of Mahendraparvata.

The only European that had been in the area as of 1936 was Phillipe Stern, a French archeologist.