Question: Who was appointed arbitrator by the first convert to the faith that is the most common religion in Southeast Asia?

Passages:
Country Population Christian Islam Irreligion Hindu Buddhist Folk religion Other religion Jewish Pop.% Pop.% Pop.% Pop.% Pop.% Pop.% Pop.% Pop.% Brunei 400,000 37,600 9.40 300,400 75.10 1,600 0.40 1,200 0.30 34,400 8.60 24,800 6.20 400 0.10 0 0.00 Burma 47,960,000 3,740,880 7.80 1,918,400 4.00 239,800 0.50 815,320 1.70 38,415,960 80.10 2,781,680 5.80 95,920 0.20 0 0.00 Cambodia 14,140,000 56,560 0.40 282,800 2.00 28,280 0.20 0 0.00 13,701,660 96.90 84,840 0.60 0 0.00 0 0.00 Indonesia 239,870,000 23,747,130 9.90 209,166,640 87.20 240,000 0.10 4,077,790 1.70 1,679,090 0.70 719,610 0.30 239,870 0.10 0 0.00 Laos 6,200,000 93,000 1.50 0 0.00 55,800 0.90 0 0.00 4,092,000 66.00 1,903,400 30.70 43,400 0.70 0 0.00 Malaysia 28,400,000 2,669,600 9.40 18,090,800 63.70 198,800 0.70 1,704,000 6.00 5,026,800 17.70 653,200 2.30 56,800 0.20 0 0.00 Philippines 105,000,000 89,000,000 85.00 5,127,000 5.50 7,350,000 7.00 10,000 0.00 1,758,000 1.50 1,398,900 1.50 93,260 0.10 28,473 0.03 Singapore 5,090,000 926,380 18.20 727,870 14.30 834,760 16.40 264,680 5.20 1,725,510 33.90 117,070 2.30 493,730 9.70 0 0.00 Thailand 69,120,000 622,080 0.90 3,801,600 5.50 207,360 0.30 69,120 0.10 64,419,840 93.20 60,000 0.09 0 0.00 0 0.00 Timor - Leste 1,120,000 1,115,520 99.60 1,120 0.10 0 0.00 0 0.00 0 0.00 1,120 0.10 0 0.00 0 0.00 Vietnam 94,700,000 7,765,400 8.20 175,700 0.20 28,031,200 29.60 151,200 0.16 15,530,800 16.40 42,899,100 45.30 351,400 0.40 0 0.00 Total 593,410,000 116,571,210 21.33 245,594,630 40.38 31,903,260 4.70 6,932,110 1.17 143,582,660 24.20 47,540,670 8.01 1,374,780 0.23 28,437 0.00 One account in Tabari says that the first male convert is Zayd ibn Harithah, a freed slave who had become Muhammad's adopted son. It is known that Ali is the first person to convert to Islam, however some dispute this arguing he was only 12 years old at the time he embraced Islam. Following this battle, Ali fought a battle against Muawiyah, known as the Battle of Siffin. The battle was stopped before either side had achieved victory, and the two parties agreed to arbitrate their dispute. After the battle Amr ibn al-As was appointed by Muawiyah as an arbitrator, and Ali appointed Abu Musa Ashaari. Seven months later, in February 658, the two arbitrators met at Adhruh, about 10 miles north west of Maan in Jordon. Amr ibn al-As convinced Abu Musa Ashaari that both Ali and Muawiyah should step down and a new Caliph be elected. Ali and his supporters were stunned by the decision which had lowered the Caliph to the status of the rebellious Muawiyah I. Ali was therefore outwitted by Muawiyah and Amr. Ali refused to accept the verdict and found himself technically in breach of his pledge to abide by the arbitration. This put Ali in a weak position even amongst his own supporters. The most vociferous opponents in Ali's camp were the very same people who had forced Ali into the ceasefire. They broke away from Ali's force, rallying under the slogan, "arbitration belongs to God alone." This group came to be known as the Kharijites ("those who leave"). In 659 Ali's forces and the Kharijites met in the Battle of Nahrawan. Although Ali won the battle, the constant conflict had begun to affect his standing, and in the following years some Syrians seem to have acclaimed Muawiyah as a rival caliph.

Supporting sentences:
Country Population Christian Islam Irreligion Hindu Buddhist Folk religion Other religion Jewish Pop.% Pop.% Pop.% Pop.% Pop.% Pop.% Pop.% Pop.% Brunei 400,000 37,600 9.40 300,400 75.10 1,600 0.40 1,200 0.30 34,400 8.60 24,800 6.20 400 0.10 0 0.00 Burma 47,960,000 3,740,880 7.80 1,918,400 4.00 239,800 0.50 815,320 1.70 38,415,960 80.10 2,781,680 5.80 95,920 0.20 0 0.00 Cambodia 14,140,000 56,560 0.40 282,800 2.00 28,280 0.20 0 0.00 13,701,660 96.90 84,840 0.60 0 0.00 0 0.00 Indonesia 239,870,000 23,747,130 9.90 209,166,640 87.20 240,000 0.10 4,077,790 1.70 1,679,090 0.70 719,610 0.30 239,870 0.10 0 0.00 Laos 6,200,000 93,000 1.50 0 0.00 55,800 0.90 0 0.00 4,092,000 66.00 1,903,400 30.70 43,400 0.70 0 0.00 Malaysia 28,400,000 2,669,600 9.40 18,090,800 63.70 198,800 0.70 1,704,000 6.00 5,026,800 17.70 653,200 2.30 56,800 0.20 0 0.00 Philippines 105,000,000 89,000,000 85.00 5,127,000 5.50 7,350,000 7.00 10,000 0.00 1,758,000 1.50 1,398,900 1.50 93,260 0.10 28,473 0.03 Singapore 5,090,000 926,380 18.20 727,870 14.30 834,760 16.40 264,680 5.20 1,725,510 33.90 117,070 2.30 493,730 9.70 0 0.00 Thailand 69,120,000 622,080 0.90 3,801,600 5.50 207,360 0.30 69,120 0.10 64,419,840 93.20 60,000 0.09 0 0.00 0 0.00 Timor - Leste 1,120,000 1,115,520 99.60 1,120 0.10 0 0.00 0 0.00 0 0.00 1,120 0.10 0 0.00 0 0.00 Vietnam 94,700,000 7,765,400 8.20 175,700 0.20 28,031,200 29.60 151,200 0.16 15,530,800 16.40 42,899,100 45.30 351,400 0.40 0 0.00 Total 593,410,000 116,571,210 21.33 245,594,630 40.38 31,903,260 4.70 6,932,110 1.17 143,582,660 24.20 47,540,670 8.01 1,374,780 0.23 28,437 0.00 It is known that Ali is the first person to convert to Islam, however some dispute this arguing he was only 12 years old at the time he embraced Islam. After the battle Amr ibn al-As was appointed by Muawiyah as an arbitrator, and Ali appointed Abu Musa Ashaari.