The first modern accounts of the ruins of the Indus civilisation are those of Charles Masson, a deserter from the East India Company's army. In 1829, Masson traveled through the princely state of Punjab, gathering useful intelligence for the Company in return for a promise of clemency. An aspect of this arrangement was the additional requirement to hand over to the Company any historical artifacts acquired during his travels. Masson, who had versed himself in the classics, especially in the military campaigns of Alexander the Great, chose for his wanderings some of the same towns that had featured in Alexander's campaigns, and whose archaeological sites had been noted by the campaign's chroniclers. Masson's major archaeological discovery in the Punjab was Harappa, a metropolis of the Indus civilization in the valley of Indus's tributary, the Ravi river. Masson made copious notes and illustrations of Harappa's rich historical artifacts, many lying half-buried. In 1842, Masson included his observations of Harappa in the book "Narrative of Various Journeys in Baluchistan, Afghanistan, and the Punjab". He dated the Harappa ruins to a period of recorded history, erroneously mistaking it to have been described earlier during Alexander's campaign. Masson was impressed by the site's extraordinary size and by several large mounds formed from long-existing erosion.