Cum non solum was a letter written by Pope Innocent IV to the Mongols on March 13, 1245.
Since not only men but also irrational animals and even the very elements of the world machine have been connected by a certain unity of natural affinity on the model of the heavenly spirits, whose hosts God the creator of the universe has established in the unending stability of a peaceful order, we are strongly compelled – not without cause – to be astonished that you, as we have heard, having invaded so many regions of the Christians as well as those of other peoples, laid waste to these with a terrible devastation; and that up to this time you, not ceasing to send pillaging bands in your continuous anger into further regions, with the restraint of natural reason broken and making no exception for age or sex, you have raged against all indifferently with the sword of your anger.
We therefore, desiring to live together by the example of the Pacific King in the unity of peace under the fear of God, warn, request, and advise your unity intently: desist completely from further attacks of this kind and especially from the persecution of Christians, and through the satisfaction of a fitting penance placate the anger of Divine Majesty which on account of so many and such great offenses you most certainly have provoked through these incitements. You ought not accordingly take up the audacity of ravaging further, because, as the sword of your power rages against others, the all-powerful Lord has so far permitted diverse nations to be laid low before you; but He in our age frequently passes over chastening the proud until the right time, so that if they neglect to become humble of their own accord, He may not hesitate to punish their wickedness in time and may exact more serious retribution in the future.
And behold, a chosen son Brother I. and his colleagues the bearers of letters, men conspicuous in religion, distinguished by honesty, and gifted with knowledge of the Holy Scripture, we have led to you concerning this matter. I ask you to receive these men generously and treat honorably as you would us by trusting them in those things they will say to you from us and holding fruitful conversation with them about the things mentioned above and especially those matters pertaining to peace. Tell us fully through these brothers what has moved you to the extermination of other peoples and what further you intend; and look after these in their coming and going through a secure conduct and other necessary things, so that they may return safe to our presence.
from "The Popes - Every Question Answered" by Rupert Matthews