SIEM REAP, CAMBODIA - “Have you heard about the lost city?” asks Sean, our Cambodian guide, who seems eager to expand our horizons beyond the temple complex of Angkor Wat.

HUAY NAM RIN, THAILAND - The morning sun glows red through the trees. The mountains they call the Golden Triangle — where the borders of Thailand, Myanmar and Laos meet — frame the scene from our balcony in the northern Thai city of Chiang Mai.