During the caliphate of Uthman the people of Tabaristan like the people of the other provinces of Persia revolted against the authority of the Muslim rule. Uthman directed Sa'ad b 'Aas the Governor General of Kufa to suppress the revolt. Sa'ad b Al 'Aas led a strong force of 80,000 warriors to Tabaristan under his personal command. The force included such eminent persons as Abdullah b Abbas; Abdullah b Umar; Abdullah b Zubair; and Abdullah b Umar b Al 'Aas .
The Muslim force advanced in the first instance to Qumas. The Persians at Qumas were not in a position to fight against such a large Muslim force. They surrendered, and peace was made subject to their payment of an annual tribute. From Qumas the Muslims advanced to Jurjan. The Persian garrison offered some resistance but finding such resistance useless surrendered. A tribute of 20 lakh dirhams was imposed on the people and peace was made.
Thereafter the Muslim force advanced to Tamlisa. It was situated on the sea coast. It was a fortified town and contained a large Persian force. The Persian force offered stiff resistance. So stiff and violent was the resistance of the Persians that Saeed b A1 'Aas had to offer Salat-i-Khauf, prayers offered on the occasion of great danger. A violent battle took place outside the city which was not conclusive. The Muslims increased their pressure, and at last the Persian garrison surrendered. The peace terms agreed upon were ambiguous, and one of the terms agreed upon was liable to the interpretation that immunity was to be allowed to one man only. Availing of the ambiguity of the term when the Persians surrendered and laid down arms, all male persons except one were executed. Women and children were made slaves. Immense booty fell into the hands of the Muslims. The harsh treatment meted out to the people of Tamlisa struck terror into the hearts of the people of other towns and they lost the will to resist the Muslims
The Muslim forces thereafter overran Gilan and other parts of Tabaristan. Even the hilly tract which had not been conquered during the caliphate of Umar was brought under Muslim rule. Having reconquerd the whole of Tabaristan Saeed b A1 'Aas planned to march to Khurasan, but when he came to know that Ibn 'Aamir the Governor General of Basra was already in };hurasan, Saeed returned to Kufa.
Ka'ab b Jamil wrote some verses in the honor of Saeed b A1 'Aas . He said:
"The bravery of young Saeed was notable; He overpowered the whole of Tabaristan; And that was a great feat; He even penetrated the hills, Heretofore inaccessible to the Muslims. He led a force of 80,000 warriors, And his efforts were crowned with success As a General and Administrator, He has surpassed his predecessors, Verily, he is a great man."