What exactly was the point of introducing Indus Valley Civilization in the beginning of the text if author was going to explain everything in context of Vedic S

What exactly was the point of introducing Indus Valley Civilization in the beginning of the text if author was going to explain everything in context of Vedic System? Vedic System or Vedas was not created/written by Indus Valley people. It was written by Aryans who brought Prakrit/Sanskrit language and spoken Vedas with them to Indian region. This is the current stand of most of the Indic historians. The script (supposedly) used by Indus Valley people has not even been deciphered, so deducing knowledge from texts supposedly written in that script is close to impossible currently. https://m.thewire.in/article/history/iit-kharagpur-vedic-calender-appropriate-indus-valley-civilisation/amp https://m.thewire.in/article/history/iit-kharagpur-vedic-cal...