Since the death of Okkodai the imperial authority had been in _interregnum_. Kuyuk, Okkodai's eldest son, had now been designated to the throne; his formal election in a great _Kurultai_, or diet of the tribes, took place while the friars were at Sira Orda, along with 3000 to 4000 envoys and deputies from all parts of Asia and eastern Europe, bearing homage, tribute and presents. They afterwards, on the 24th of August, witnessed the formal enthronement at another camp in the vicinity called the Golden Ordu, after which they were presented to the emperor. It was not till November that they got their dismissal, bearing a letter to the pope in Mongol, Arabic and Latin, which was little else than a brief imperious assertion of the khan's office as the scourge of God. Then commenced their long winter journey homeward; often they had to lie on the bare snow, or on the ground scraped bare of snow with the traveller's foot. They reached Kiev on the 9th of June 1247. There, and on their further journey, the Slavonic Christians welcomed them as risen from the dead, with festive hospitality. Crossing the Rhine at Cologne, they found the pope still at Lyons, and there delivered their report and the khan's letter.
Not long afterwards Friar Joannes was rewarded with the archbishopric of Antivari in Dalmatia, and was sent as legate to St Louis. The date of his death may be fixed, with the help of the _Franciscan Martyrology_ and other authorities, as the 1st of August 1252; hence it is clear that John did not long survive the hardships of his journey.
He recorded the information that he had collected in a work, variously entitled in the MSS. _Historia Mongalorum quos nos Tartaros appellamus_, and _Liber Tartarorum_, or _Tatarorum_. This treatise is divided into eight ample chapters on the country, climate, manners, religion, character, history, policy and tactics of the Tatars, and on the best way of opposing them, followed by a single (ninth) chapter on the regions passed through. The book thus answers to its title. Like some other famous medieval itineraries it shows an entire absence of a traveller's or author's egotism, and contains, even in the last chapter, scarcely any personal narrative. Carpini was not only an old man when he went cheerfully upon this mission, but was, as we know from accidental evidence in the annals of his order, a fat and heavy man (_vir gravis et corpulentus_), insomuch that during his preachings in Germany he was fain, contrary to Franciscan precedent, to ride a donkey. Yet not a word approaching more nearly to complaint than those which we have quoted above appears in his narrative. His book, both as to personal and geographical detail, is inferior to that written a few years later by a younger brother of the same Order, Louis IX.'s most noteworthy envoy to the Mongols, William of Rubrouck or Rubruquis. But in spite of these defects, due partly to his conception of his task, and in spite of the credulity with which he incorporates the Oriental tales, sometimes of childish absurdity, from which Rubruquis is so free, Friar Joannes' _Historia_ is in many ways the chief literary memorial of European overland expansion before Marco Polo. It first revealed the Mongol world to Catholic Christendom; its account of Tatar manners, customs and history is perhaps the best treatment of the subject by any Christian writer of the middle ages. We may especially notice, moreover, its four name-lists:--of the nations conquered by the Mongols; of the nations which had up to this time (1245-1247) successfully resisted; of the Mongol princes; and of the witnesses to the truth of his narrative, including various merchants trading in Kiev whom he had met. All these catalogues, unrivalled in Western medieval literature, are of the utmost historical value. To the accuracy of Carpini's statements upon Mongol life, a modern educated Mongol, Galsang Gomboyev, has borne detailed and interesting testimony (see _Mélanges asiat. tirés du Bullet. Hist. Philol. de l'Acad. Imp. de St Pétersbourg_, ii. p. 650, 1856).