Burlap, also known as sackcloth, was made from goat or camel hair. People often used it for grain sacks or to carry items on pack animals. Poor people wore it as clothing because it was cheap. People in mourning wore it to show their deep sorrow. Its dark color matched their mood, and its roughness matched their discomfort.
Throwing dust on their heads and clothing signaled to neighbors that a family member had died.