It is more accurate to judge by the principle of geomantic omen, because ancient geomantic omen has penetrated into all walks of life, and many people still believe it until now. Therefore, the tombs of the ancients were basically buried according to the principle of geomantic omen, so looking for ancient tombs from the perspective of geomantic omen will get twice the result with half the effort!
Other methods, such as distinguishing soil color, looking at topography and geology, can also judge whether there are ancient tombs.