He was appointed to oversee vast lands from
Oxus to
Anatolia with Sharaf al-Din Khwarazmi as his secretary, whom he had a distaste in. His position was reaffirmed by
Güyük Khan in 1246.
Ascelin of Lombardia might have met him while he was at the court of
Baiju in . He visited
Karakorum twice after his appointment in 1248 and 1251. On his third voyage, he was upheld by
Hulagu in Transoxiana and was released after a while. His employees included the famous
Juvayni family, Fakr al-Din Bihishti (d. 1256), Husam al-Din Bihishti, Najm al-Din Ali, Turumtai, Naimadai, etc. He made a census in Persia in accordance with the decree of
Möngke in 1254 along with Najm al-Din Ali. In 1259-61 he directed punitive operations against rebels in
Georgia. When in 1260
Hulegu Khan requested the presence of
Georgians and
Armenians for the
Mongol invasions of the Levant,
David Ulu, king of the
Eastern Kingdom of Georgia rebelled, remembering the losses of his troops in the 1258
Siege of Baghdad. A large Mongol army led by Arghun Aqa invaded Georgia from the south, inflicted a heavy defeat on David and
Sargis I Jaqeli in a battle near
Akhaldaba, and then brutally plundered the country. The Mongol campaign continued during the winter, and the following year king David Ulu was forced to flee to
Imereti, which the Mongols failed to conquer. David's family was captured, and his wife
Gvantsa was killed. Peace with the Mongols was achieved in 1262, when David Ulu returned to
Tbilisi to reclaim his crown as a Mongol vassal, pledging allegiance to
Hulegu, while David Narin nominally recognized Mongol rule in Imereti. Hulegu tolerated the rebel because since 1261, the Il-kan was at war with the
Berke of
Golden Horde, which was on a larger scale. Arghun had many political enemies at the headquarters, so he had to visit the
ordo of the Qaghan in
Mongolia often to prove his loyalty. Although, Möngke appointed him to his former position after his accession in 1252, the Emperor summoned Arghun to answer a charge of treason. The
Armenian noble,
Sempad Orpelian, justified Arghun completely and charged his enemy, a
Khorazmi lieutenant, with being the real offender. Arghun was released and they returned together.
Under Hulagu He mainted his administrative tasks under Hulagu and even punished underpaying vassals who owed them taxes, including
Gvantsa Kakhaberidze,
Hasan Jalal of Khachen,
Zakare III Zakarian,
Akhsitan II and others in 1261. He accompanied
Prince Abaqa in support of
Alghu against his struggle with
Golden Horde.
Under Abaqa Arghun continued to serve Ilkhanate after death of Hulagu in 1265. His new post was in
Khorasan, as deputy of Prince Tubshin. New Chagatai khan
Baraq threatened to invade Ilkhanate until they leave
Afghanistan to them in 1270. Arghun Aqa fought in left flank under
Prince Yoshmut in Battle of Herat on 22 July 1270 which resulted in a decisive victory. He served in Khorasan till his death on 17 June 1275. == Legacy ==