It is clear now that from the very start, the hunters’ abduction was linked to the civil war in Syria, which has drawn in regional powers in an increasingly complicated proxy war. On one side of the hostage negotiations were Shiite powers — Iran and its Lebanese proxy Hezbollah — which firmly support the Syrian government of Bashar al-Assad. On the other were the Sunni powers Qatar and Turkey, which fund and arm rebel groups trying to take down Mr. Assad’s government.

Their release, which involved the payment of millions of dollars in ransom to an Iraqi militia backed by Iran, was tied to a broader deal involving a trading of besieged sectarian populations among four towns in Syria, according to a senior Shiite leader in Iraq who spoke on the condition of anonymity because of the sensitivity of the subject.

The Iraqi Shiite official said the release of the Qatari prisoners was linked to the safe evacuation of — and delivery of humanitarian aid to — residents of two Shiite villages in Idlib Province, Fouaa and Kfarya. They have been under government control but besieged by Sunni Islamist rebel groups backed by Turkey and Qatar.

The Syrian deal was negotiated separately before the fate of the hostages became entwined with the talks. As part of that agreement, residents of two predominantly Sunni villages, Madaya and Zabadani, that have been held by rebels but besieged by forces loyal to the Syrian government are to be bused to safety. Many of them, about 2,000 people, have already been evacuated from Madaya.