We have a nice example from the Crusade era in 1167 which may be up your street:

During this time both the Latin kingdom of Jerusalem (crusaders) and their regional rival, Nur ed-Din, had designs on Egypt, which was economically rich but militarily frail. The young Egyptian caliph al-Adid and his pragmatic vizier Shawar therefore changed alliances with their powerful neighbours often, so that one could protect them from the other. In 1167 the troops of Nur ed-Din once again move against Egypt, under control of his favoured general Shirkuh (the uncle of Saladin), causing the Egyptian Shawar to appeal for help from the Franks. The king of Jerusalem Amalric I is receptive and thus begins this interesting glimpse into their diplomacy.

William of Tyre reports that the king's fee was 400,000 gold pieces, half of which was to be paid immediately, up front. Such an agreement demanded the personal guarantee of the caliph himself and William's record of the resultant meeting emphasises his astonishing access to first-person accounts of the campaign and its preceding diplomacy. The Frankish representative was Hugh of Caesaria, a royal favourite and commander in Amalric's army. William describes the journey through Cairo's palace complex, with each advancement closer to the caliph growing exponentially in grandeur and luxury. The caliph, al-Adid, still a teenager, was eventually revealed with theatrical ceremony from behind a golden veil. When the pact for aid was struck, Hugh put out his hand to shake and solemnify their agreement in good faith, as was customary in European cultural tradition, much to the horror of the caliph's assembled courtiers. The idea that this Frankish lord should presume to touch al-Adid was, to the palace entourage at least, 'utterly beyond comprehension'. When the young caliph eventually offered his delicately gloved hand, Hugh insisted that the exposed skin of sealing a bond by the shaking of hands was the pertinent component of the act, causing further disquiet in the chamber. It took the pleading of the caliph's desperate vizier for al-Adid to finally acquiesce. This episode is a mere vignette in the period's history but endlessly powerful as a piece of cultural commentary.

The most important part of diplomacy in the Near East was pragmatism and as a result these diplomatic events between very different cultures and societies are frequent. They serve to illustrate the friction of co-existence between parties with little in common who were necessarily forced together for expediency.

The account above in its first Latin form is from:

William of Tyre - A History of Deeds Done Beyond the Sea

The classic 20thC commentary on the account is perhaps:

Runciman - History of the Crusades

For the best current literautre I would suggest:

Tyreman - God's War

and

Asbridge - The Crusades

I hope this was helpful and along the lines of what you were looking for.

Edit: Formatting.