[SC求助］OG一个句法题的长难句翻译

Excavators at the Indus Valley site of Harappa in eastern Pakistan say the discovery of inscribed shards dating to circa 2800-2600 B.C. indicates that the development of a Harappan writing system, the use of inscribed seals impressed into clay for marking ownership, and the standardization of weights for trade or taxation occurred many decades, if not centuries, earlier than was previously believed.

正确句子已替换进原文中，请教各位大神这句话的中文翻译。感谢！