Bakr, likely understanding that maintaining firm control over the disparate tribes of Arabia was crucial to ensuring the survival of the state, suppressed the insurrections with military force. He dispatched Khalid ibn Walid and a body of troops to subdue the uprisings in Najd as well as that of Musaylimah, who posed the most serious threat. Concurrent to this, Shurahbil ibn Hasana and Al-Ala'a Al-Hadrami were sent to Bahrayn, while Ikrimah ibn Abi Jahl, Hudhayfah al-Bariqi and Arfaja al-Bariqi were instructed to conquer Oman. Finally, Al-Muhajir ibn Abi Umayya and Khalid ibn Asid were sent to Yemen to aid the local governor in re-establishing control. Abu Bakr also made use of diplomatic means in addition to military measures. Like Muhammad before him, he used marriage alliances and financial incentives to bind former enemies to the caliphate. For instance, a member of the Banu Hanifa who had sided with the Muslims was rewarded with the granting of a land estate. Similarly, a Kindah rebel named Al-Ash'ath ibn Qays, after repenting and re-joining Islam, was later given land in Medina as well as the hand of Abu Bakr's sister Umm Farwa in marriage. At their heart, the Ridda movements were challenges to the political and religious supremacy of the Islamic state. Through his success in suppressing the insurrections, Abu Bakr had in effect continued the political consolidation which had begun under Muhammad's leadership with relatively little interruption. By wars' end, he had established an Islamic hegemony over the entirety of the Arabian Peninsula. Expeditions into Persia and Syria With Arabia having united under a single centralised state with a formidable military, the region could now be viewed as a potential threat to the neighbouring Byzantine and Sasanian empires. It may be that Abu Bakr, reasoning that it was inevitable that one of these powers would launch a pre-emptive strike against the youthful caliphate, decided that it was better to deliver the first blow himself. Regardless of the caliph's motivations, in 633, small forces were dispatched into Iraq and Palestine, capturing several towns. Though the Byzantines and Sassanians were certain to retaliate, Abu Bakr had reason to be confident; the two empires were militarily exhausted after centuries of war against each other, making it likely that any forces sent to Arabia would be diminished and weakened. A more pressing advantage though was the effectiveness of the Muslim fighters as well as their zeal,