An archeological artifact is a PRIMARY OR SECONDARY SOUCE

Primary

Explanation:

Quoting from the wiki, "In the study of history as an academic discipline, a primary source (also called an original source) is an artifact, document, diary, manuscript, autobiography, recording, or any other source of information that was created at the time under study."

early settlements on the subcontinent. both the indus and the ganges rivers carried rich silt from the mountains to the plains. when the rivers flooded, the silt spread over the plains and made the soil in the river valleys fertile for farming.