The Catholic Church and the Assyrian Church were one Church for about 400 years, but disagreement with the Council of Ephesus in 431 AD led to the Assyrian Church breaking communion with Rome.
There are also the Oriental Orthodox, who broke communion when they did not accept the Council of Chalcedon in 451 AD, and the Eastern Orthodox who broke communion with Rome (and vice versa) due to the events of the Great Schism in the 11th century. There are some particular Churches from these that have since entered back into communion with Rome, but not all. This is all broad strokes, and it gets more nuanced than that.
The Roman Catholic Church, Eastern Orthodox, Oriental Orthodox, and Assyrian Church all have legitimate claims to being apostolic Churches, that is, continuations of particular Churches founded by the Apostles. This doesn’t mean the Catholic Church considers them all to be in 100% right order, but this is different than the branches of Protestant and Reconstructionist movements, which by Catholic teaching have lost their Apostolic succession and have different understandings of the Church, sacraments, etc…
This graphic may help.
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