The Indus Valley Civilization remains one of the most enigmatic events in human history, if only for the paucity of knowledge associated with it in general discourse. It was truly a paean to the desire for human excellence, even in those times, bringing in its wake several important inventions which mankind has derived progress from. <span>Each and every one of the 4 ancient civilizations had its own mind boggling languages, handicrafts, religion et al. Here I am only concentrating on the amazing and unique things found exclusively in Indus Valley Civilization.</span>
https://quizlet.com/24479197/govt-2305-ch15-flash-cards/
This may help....if not sorry but you have extra notes.
This is because iron is more reactive than copper in the metal reactivity series.