When were Banu Hashim besieged, and how was the siege lifted?

The unjust siege laid by Quraysh against the Prophet Muhammad (peace be upon him) and those with him from Banu Hashim and Banu Al-Muttalib in the valley of Abu Talib began at the start of Muharram in the seventh year of his prophethood and lasted for three years. Quraysh had covenanted not to deal with Banu Hashim and Banu Al-Muttalib until they handed over the Prophet (peace be upon him) to them, and they wrote a document to this effect. Banu Hashim and Banu Al-Muttalib, both their believers and disbelievers—except for Abu Lahab—sided together, and the Prophet and those with him were confined in the valley, facing severe hardship in their livelihood.

Allah informed His Prophet that the termites had eaten the document except for the mention of Allah. The Prophet then informed his uncle of this, and when the document was exposed and they found the matter to be as he had stated, they increased in their disbelief and obstinacy. The Prophet and those with him left the valley in the tenth year of his prophethood. A group of wise men from Quraysh worked to nullify the document, and they were: Hisham ibn Amr, Zuhayr ibn Abi Umayya, Abu Al-Bakhtari ibn Hisham, Zam'ah ibn Al-Aswad, and Mut'im ibn Adi.