After being put into bat, Assam made 100 from 11 overs riding mainly on Rishav Das' 29-ball 50 which was studded with eight fours and one six.
For Jharkand, left-arm spinners Shabaz Nadeem and Sarfaraz Ashraf picked up two wickets each.
Jharkand, however, did not have the best of starts as they lost opener Virat Singh (2) early, dismissed by Swarupam Purkayastha in the third ball of their innings.
Jaggi and Tiwary put on an unbeaten 64-run stand for the third wicket to guide Jharkand.
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Meanwhile in the other East Zone match of the day, despite losing by a narrow one win to Bengal, hosts Odisha managed to join Jharkhand in the Super League stage of the tournament.
Bengal rode on skipper Laxmi Ratan Shukla's unbeaten 35-ball 47 to set up a thrilling one-run consolation win.
Having chosen to bat, Bengal made a strong total of 168 for six, thanks to Wriddhiman Saha's 15-ball 33 at the top of the order, Shukla's fireworks, and good hands from Manoj Tiwary (21) and Sudip Chatterjee (27).
Chasing the terget, Govinda Podder's 28-ball 36 kept Odisha in the hunt, but they were well behind the asking rate when he was dismissed in the 16th over, and needed 63 to win off tghe last five overs with five wickets in hand.