Abu Sallh records in the 12th century that the patriarch used always to send letters twice a year to the kings of Abyssinia and Nubia, till Al Hakim stopped the practice. Cyril, 67th patriarch, sent Severus as bishop, with orders to put down polygamy and to enforce observance of canonical consecration for all churches. These examples show the close relations of the two churches in the Middle Ages. But early in the 16th century the church was brought under the influence of a Portuguese mission.
In 1439, in the reign of Zara Yakub, a religious discussion between an Abyssinian, Abba Giorgis, and a Frank had led to the despatch of an embassy from Abyssinia to the Vatican; but the initiative in the Roman Catholic missions to Abyssinia was taken, not by Rome, but by Portugal, as an incident in the struggle with the Mussulmans for the command of the trade route to India by the Red Sea.
In 1507 Matthew, or Matheus, an Armenian, had been sent as Abyssinian envoy to Portugal to ask aid against the Muslims, and in 1520 an embassy under Dom Rodrigo de Lima landed in Abyssinia. An interesting account of this mission, which remained for several years, was written by Francisco Alvarez, the chaplain.
Later, Ignatius Loyola wished to essay the task of conversion, but was forbidden. Instead, the pope sent out Joao Nunez Barreto as patriarch of the East Indies, with Andre de Oviedo as bishop; and from Goa envoys went to Abyssinia, followed by Oviedo himself, to secure the king's adherence to Rome. After repeated failures some measure of success was achieved, but not till 1604 did the king make formal submission to the pope. Then the people rebelled and the king was slain. Fresh Jesuit victories were followed sooner or later by fresh revolt, and Roman rule hardly triumphed when once for all it was overthrown. In 1633 the Jesuits were expelled and allegiance to Alexandria resumed.
There are many early rock-cut churches in Abyssinia, closely resembling the Coptic. After these, two main types of architecture are found -- one basilican, the other native. The cathedral at Axum is basilican, though the early basilicas are nearly all in ruin; e.g., that at Adulis and that of Martula Mariam in Gojam, rebuilt in the 16th century on the ancient foundations. These examples show the influence of those architects who, in the 6th century, built the splendid basilicas at Sanaa and elsewhere in Arabia. Of native churches there are two forms -- one square or oblong, found in Tigre; the other circular, found in Amhara and Shoa. In both, the sanctuary is square and stands clear in the centre. An outer court, circular or rectangular, surrounds the body of the church. The square type may be due to basilican influence, the circular is a mere adaptation of the native hut: in both, the arrangements are obviously based on Jewish tradition. Church and outer court are usually thatched, with wattled or mud-built walls adorned with rude frescoes. The altar is a board on four wooden pillars having upon it a small slab (tabut) of alabaster, marble, or shittim wood, which forms its essential part. At Martula Mariam, the wooden altar overlaid with gold had two slabs of solid gold, one 500, the other 800 ounces in weight. The ark kept at Axum is described as two feet high, covered with gold and gems. The liturgy was celebrated on it in the king's palace at Christmas, Epiphany, Easter and Feast of the Cross.
Generally the Abyssinians agree with the Copts in ritual and practice. The LXX version was translated into Geez, the literary language, which is used for all services, though hardly understood. Saints and angels are highly revered, if not adored, but graven images are forbidden. Fasts are long and rigid. Confession and absolution, strictly enforced, give great power to the priesthood. The clergy must marry, but once only. Pilgrimage to Jerusalem is a religious duty and covers many sins.