The Mishnah argues that the ritually clean locusts could be distinguished as they would all have four feet, jumping with two of them, and have four wings which are of sufficient size to cover the entire locust's body. The Mishnah also goes on to state that any species of locust could only be considered as clean if there was a reliable tradition that it was so. The only Jewish group that continue to preserve such a tradition are the Jews of Yemen, who use the term kosher locust to describe the specific species of locusts they believe to be kosher, all of which are native to the Arabian Peninsula. Due to the difficulties in establishing the validity of such traditions, later rabbinical authorities forbade contact with all types of locust to ensure that the ritually unclean locusts were avoided.