6. The agriculture ritual that Karen have practiced for generations is called Nam - rai, a ceremony to make the beginning of using a particular plot of land for farming. The ceremony is believed to ensure sustainability of the land for the next generation. First, a wooden frame is built around the plot of land. The men dig seven holes in the land with two - meter long spades with bamboo handles, called ma nga bo. The Karen believe the ma - nga bo will preserve the land and keep the soil. fertile. Then a man and woman - both young and single - lead the ceremony by adding seeds to the seven holes. The Karen believe that young virgins bring good luck and a plentiful crop.