Which Inner Mongolian desert is famous for tall dunes and many interdunal lakes?

The Inner Mongolian desert famous for tall dunes and numerous interdunal lakes is the Badain Jaran Desert.

Badain Jaran lies mainly in Inner Mongolia, with parts extending into Gansu and Ningxia in China. It covers about 49,000 square kilometres and is noted for immense megadunes, including stationary dunes rising more than 500 metres from base to summit. Bilutu Peak is widely described as the world's highest stationary dune.

The desert's other great distinction is its network of lakes between the dunes. More than 100 spring-fed or groundwater-supported lakes are scattered through the sandy terrain. Some are relatively fresh, while others are highly saline; algae, minerals, and evaporation can give individual lakes striking colours. Their persistence in such an arid landscape has made the movement of underground water a major subject of scientific study.

The name is often translated as “mysterious lakes,” reflecting this unusual landscape. The Tengger Desert lies nearby to the east, while the Kumtag and Ordos deserts are separate Chinese desert regions. Badain Jaran is the answer because the combination of giant dunes and clustered interdunal lakes is especially distinctive.