Later they began placing the tokens in large, hollow, clay containers (bulla) which were sealed; the quantity of tokens in each container came to be expressed by impressing, on the container's surface, one picture for each instance of the token inside.
Later they began placing the tokens inside large, hollow clay containers (globular envelopes, or bulla) which were sealed. The quantity of tokens in each container came to be expressed by impressing, on the container's surface, one picture for each instance of the token inside.