Inspired by haralampopoulosjc
1009 - Pope Sergius IV of Rome uses filioque in the creed in a letter to Patriarch Sergius II of Constantinople and Constantinople removes Rome from the diptychs. (Possibly a latter legend)
1054 - Rome breaks communion with the Ecumenical Patriarchate of Constantinople.
1099 - Rome establishes a Latin patriarch of Jerusalem, thus breaking communion with the actual Jerusalem Patriarchate.
1100 - Rome establishes a Latin patriarchate in Antioch thus breaking communion with the actual Antiochian Patriarchate.
1191 Cyprus was militarily occupied by the Raynald of Châtillon, establishing the Latin Kingdom of Cyprus between 1119 - 1489, and subjugating the Church of Cyrpus under the pope between 1260 - 1571
1235 - Bulgarian Patriarchate voluntarily breaks communion with Rome.
Sometime after 1215 and before 1274/1310 - Alexandria likely continued to recognize Rome as late as 1215, when Patriarch Nicholas I of Alexandria sent legates to Rome’s Fourth Lateran Council. The false Reunion Coucil of Second Lyons in 1274 makes no mention of retaining communion with Alexandria and sought reunion with the whole east. 1310 Rome establishes a Latin patriarchate in Alexandria.
Sometime before 1240 - Queen Rusudan of Georgia sends a letter to Pope Gregory IX in Rome before 1240, which was brought to Rome by Giacomo da Rosano. This is confirmed by the pope’s reply written on 13 January 1240. The Georgian Queen’s letter to the Pope is still unknown, but the addressee’s reply shows what the Queen of Georgia was asking him. First, to provide military assistance against the Mongols and second, to unite her people in the Catholic Church. To the first request, the Pope answered with regret that the army could not help Georgia, because the powerful Muslims located between their countries would not let the army pass. There were also mentioned some other reasons: the fight against heretical Cathars in the West; complicated relationship with Friedrich II and the long distance. As for the second request, the intention of Queen Rusudan about uniting the Churches, the Pope "called it the best example of the divine foresight". Naturally, the Pope could not hide his joy and admiration. Because, while the "disastrous Schism was raging" in Europe, "unknown kings and people, so distant from him, were asking him to unite them in his Holy domain". Since Queen Rusudan was asking him to unite the Churches the Pope wrote: "As for your offer and request of uniting your spiritual house with ours, we approve your generosity, because this wish of yours will strongly and properly help your salvation and our delight with you" This proposed union was never approved or accepted by the Gregorian synod as far as I know but does definitely show there was a break of communion before this point.