He-Man and the Masters of the Universe (1983)

S2E20 Attack from Below

As Teela and Orko stroll back from admiring a farmer's impressive harvest, the ground begins to shake violently, causing entire fields to vanish. In the chaos, Teela is pulled underground and discovers a hidden society known as the Belats. While Orko frantically tries to alert others, the Belat King, Subternias, captures Teela, driven by his desperate need to provide for his people. Teela soon realizes that the Belats aren’t malevolent; rather, they are deeply wary due to past deceit by Skeletor, which has left them hesitant to trust outsiders.