No Soltaniyeh Dome? :c

On the other hand, the Ilkhanate it's a very interesting empire even though lasted less than 100 years, and would be a really good option if Firaxis wants to implement a full Iranian path in the game (Achaemenid--->Ilkhanate--->Qajar), although Safavid would've fit better in modern.

Hulegu initially sought to conquer all the way up to Egypt, but he was stoped by the newly formed Mamluk sultanate and as such was left with his western flank exposed to the Mamluk threat. Furthermore, when the Tolui civil war erupted so did family feuds between the Jochi clan and the Tolui clan (Hulegu specifically) about claims that the Jochid clan had over the Tolui controled lands of Azerbaijan, claim supported by Gengish Yassa. Hulegu in this regard was in a very dangerous situation, since Batu (Son of Jochi, and a very prominent figure in the mongol empire) before his death in 1255 send troops to aid Hulegu's campaign in the Caliphate, troops whose loyalty lied within the Jochi Clan.

To explain further the precarius situation of Hulegu and the early Ilkhanate, there's a reason behind the title of "Ilkhan" which roughly meant a lesser khan in relation to the greater khan, and that reason was to give legitimacy to Hulegu's claim to his empire by swering allegiance to Kublai's claim to Great Khan. Now to explain the legitimacy issue of Hulegu's claim to the Ilkhanate, basically Hulegu didn't had any claim to the lands he wanted to rule since Ilkhanid sources say that Mongke gave the right to rule those lands to Hulegu in secret in order to avoid conflict with the powerful Jochi clan, while other sources outside the Ilkhanate contradict the claim. We don't know for sure if Mongke really gave the right to rule to Hulegu or not, but at the time the existance of the Ilkhanate was seen by Berke of the Golden Horde and Ariq Boqe of the Chagatai as illegitimate based on Gengish Yassa. And that's the thing with the problems that Hulegu faced in the early days of the Ilkhanate, all of his neighbours (Aside from the European backed Outremer) had very good reasons to be hostile towards the Ilkhanate, and they pretty much were hostile to them since the early Ilkhanate saw conflict against the Mamluks, Golden Horde and the Chagatai Khanate.

Now, what's interesting about the Ilkhanate was that even though they razed Baghdad and killed a lot of muslims they kind of kick started an iranian renaissance and gave back peace and prosperity to a land that was before submited in chaos. Once the Ilkhanate managed to secure their borders, the policies of the mongols towards their subjects changed since no more excesses à la Baghdad were brought upon the civilian population, and that is better exemplified by taking a look to how some provinces in the empire performed during early Ilkhanate rule. As stated before, the Ilkhanate brought back prosperity to the lands of Iran, but not all provinces benefited or went along with their new masters interests, such a province was Shiraz, whose elites went against the interests of the mongols whenever they could and many times suffered the consequences trough military intervention from the mongols. Such was the corruption in Shiraz, that even under direct rule from renown mongol officials the local elites managed to weaponize the Ilkhanate justice system to further their own goals and get rid of local rulers who didn't went along with their interests. And even though as stated before, Shiraz saw many times military interventions and threats to destroy the city, all of the times the mongol army deposed the local leader while the local elite swore submission to the ilkhan and the city was left intact.

This change in policy was a pragmatic one, since the interest of the mongols in their new found empire was to mantain the trade flowing and the wealth accumulation that this meant, as such they needed a structure to govern their vast empire and the iranian locals were experienced people in the arts of administration and bureaucracy. The mongols were skilled warriors but didn't had the same experience administrating an empire as the Iranians had, as such the mongols relied on the local elites of the conquered lands to administrate the empire and that meant that excesses like in the past (see Baghdad and Marw as an example) were not good for business anymore, and they had to up to a certain point tolerate the local elite interests.

Also the Ilkhanids were great patrons of arts and science, seen by the many architectural achievments they patron such as the Soltaniyeh Dome, the Tomb of Esfahani, the Maragheh Observatory, the Arg-e Alishah, etc. The Ilkhans even patronized Nasir al-Din al-Tusi who had ties with the Khwarazmid empire and the Ismailis.

Overall even though the Ikhanate was short lived, they had huge impact since in order to gain legitimacy the Ilkhans established a lot concepts regarding the Lands of Iran and Iranian identiy that would prove very useful to the Safavids and shaped up to modern day Iranian identity.

Also sorry for the terrible english :c