How many 40 lb bags make a yard?

Excuse me, I'm a bit confused about the conversion here. Could you please clarify for me? Are you asking about how many 40-pound bags are needed to fill up a yard of space, or is it perhaps a question about a specific material where we're trying to calculate the number of bags needed for a yard of that particular material? If it's the latter, could you please specify the material, as the answer would vary depending on the density and other factors of the material?