Under Arghun After the overthrow of
Tekuder in 1284, Ghazan's father Arghun was enthroned as Ilkhan, the 11-year-old Ghazan became viceroy, and he moved to the capital of
Khorasan, never to see Arghun again. Emir Tegene was appointed as his deputy, who he didn't like very much. In 1289, conflict with other Mongols ensued when a revolt was led against Arghun by
Nawruz, a young emir of the
Oirat clan, whose father had been civil governor of Persia before the arrival of Hulegu. Ghazan's deputy Tegene was among the victims of Nawruz's raid on 20 April 1289 in which he was captured and imprisoned. Nawruz's protege, Prince Hulachu was arrested by Ghazan's commander
Mulay ten days later. When Nawruz was defeated by Arghun's reinforcements in 1290, he fled the Ilkhanate and joined the alliance of
Kaidu, another descendant of Genghis Khan who was the ruler of both the
House of Ögedei and the neighboring
Chagatai Khanate. Ghazan spent the next ten years defending the frontier of the Ilkhanate against incursions by the Chagatai Khanate of Central Asia.
Under Gaykhatu When his father, Arghun, died in 1291, Ghazan was prevented from pursuing his claim of leadership in the capital because he was engaged both with Nawruz's raids, and dealing with rebellion and famine in Khorasan and
Nishapur.
Taghachar, an army commander who had served the previous three generations of Ilkhans, was probably behind the death of Arghun, and supported Ghazan's uncle
Gaykhatu as the new Ilkhan. Despite being boyhood rivals, Gaykhatu sent aid to Ghazan's fight against Nawruz in Khorasan under the leadership of Prince Anbarchi (son of
Möngke Temür) and emirs Tuladai, Quncuqbal and El Temür; himself going to Anatolia to quell
Turcoman uprisings. However, famine reached his court too in spring and Anbarchi, unable to feed his soldiers, had to leave soon for Azerbaijan again. He again tried to visit Gaykhatu, but after his refusal, he had to go back. Ghazan received
Kököchin, a Mongol princess from the
Yuan dynasty in China, on his way back from
Tabriz to Khorasan. She had been brought from the east in a caravan which included
Marco Polo among hundreds of other travellers. She had originally been betrothed to Ghazan's father, IlKhan Arghun, but since he had died during her months-long journey, she instead married his son Ghazan. In 1294, Ghazan forced Nawruz to surrender at
Nishapur and Nawruz then became one of Ghazan's lieutenants. Ghazan was loyal to his uncle, though he refused to follow Gaykhatu's lead in introducing
paper currency to his province, explaining that the weather of Khorasan was too humid to handle paper.
Against Baydu In 1295,
Taghachar and his conspirators, who probably had been behind the death of Arghun, had his successor Gaykhatu killed as well. They then placed the pliable
Baydu, a cousin of Ghazan, on the throne. Baydu was primarily a figurehead, allowing the conspirators to divide the Ilkhanate among themselves. Hearing of Gaykhatu's murder, Ghazan marched on Baydu. Baydu explained that Ghazan was away during the events leading to Gaykhatu's fall, therefore nobles had no choice but to raise him to throne. Nevertheless, Nawruz encouraged Ghazan to take steps against Baydu, because he was nothing but a figurehead under grips of nobles. Baydu's forces commanded by Ildar (his cousin and Prince Ajay's son), Eljidei and Chichak met him near
Qazvin. Ghazan's army were commanded by Prince Sogai (son of
Yoshmut), Buralghi, Nawruz,
Qutluqshah and Nurin Aqa. The first battle was won by Ghazan but he had to fall back after realising that Ildar's contingent was just a fraction of the whole army he faced, leaving Nawruz behind. Nevertheless, he captured Arslan, a descendant of
Jochi Qasar.
Conversion to Islam After a short truce, Baydu offered Ghazan co-rulership of the Ilkhanate and offered Nawruz the post of
sahib-i divan to which as a counter-condition Ghazan demanded the revenues of his father's hereditary lands in
Fars,
Persian Iraq and
Kerman. Nawruz refused these conditions, which led to his arrest. According to an anecdote, he promised to bring Ghazan back tied up on condition of his release. Once he reached Ghazan, he sent back a
cauldron to Baydu; a word play on the Turkish word
kazan. Nawruz promised him the throne and his help on condition of Ghazan's conversion to
Islam. Ghazan converted to
Sunni Islam, on June 16, 1295, at the hands of
Ibrahim ibn Muhammad ibn al-Mu'ayyid ibn Hamaweyh al-Khurasani al-Juwayni as a condition for Nawruz's military support. Before converting to Islam based on a political agreement, Ghazan, a neo-Muslim, married his stepmother Bulughan Khatun Muazzema after his father's death, in accordance with the Mongol pagan
Yasa customs. After being informed that it was forbidden by Islamic law, he ignored it and broke the agreement by leaving Islam, leading to the massacre of Syrian Muslims and the conversion of millions of neo-Muslim Tatars in his kingdom to their former religion. In order to dissuade him from doing so, some jurists, considering
Maslaha, temporarily considered the marriage legal and encouraged him to remain in Islam, thus saving him from the great harm of Muslim genocide and apostasy and giving Ghazan a long time and opportunity to realize his mistake, so he remained in Islam. Nawruz entered
Qazvin with 4,000 soldiers and claimed an additional number of 120,000 soldiers commanded by Ebügen (in other sources, 30,000) – descendant of Jochi Qasar – on his way towards Azerbaijan which caused panic among masses which was followed by defections of Taghachar's subordinates (thanks to Taghachar's vizier Sadr ul-Din Zanjani) and other powerful emirs like Qurumishi and
Chupan on 28 August 1295. Seeing imminent defeat, Baydu asked for Taghachar's support, ignorant of his defection. After realising Taghachar's withdrawal, he fled to Emir Tukal in
Georgia on 26 September 1295. Ghazan's commanders found him near
Nakhchivan and arrested him, taking back to
Tabriz, having him executed on October 4, 1295. == Early reign ==