Cattle, with their herders, crossing the river Niger at DiafarabÂ?This is an interesting and characteristic festival that takes place every year at the beginning of December in the Sahel. Fulani herders return to the pasturelands of the south, from the north of the country, and cross the Niger at the time of year when the water is most shallow. Families celebrate being reunited after many months apart and it is a festive occasion. - - General: General.