Long before the arrival of European farming methods, the indigenous peoples of the region practiced an agricultural technique known as the Three Sisters, planting corn, beans, and squash together in mounds of dirt. Codified into native oral tradition, this practice predates the similar European practice of crop rotation. Because the plants nurture and shelter each other, with corn providing support, beans nitrogenizing the soil, and squash shielding the roots, these crops were understood as interdependent and strongest when grown together.