Well, there are paintings or frescos of Mary dating back to the 2nd or early 3rd century. For example, a fresco in the Catacomb of Priscilla in Rome, dated around 150–200 AD shows Mary with the infant Jesus, and another wall painting from Dura-Europos (circa 240 AD) may also depict her.
Early Christian art focused more on wall paintings, sarcophagi reliefs, and symbolic motifs in catacombs, partly due to the underground nature of much early Christian practice before Constantine’s legalization of Christianity in 313 AD
There was no reason for the first council of Nicea to mention Mary. The council’s primary focus was on the Arian controversy, affirming the divinity of Christ and producing the original Nicene Creed, which emphasizes Christ’s incarnation
Discussions of Mary’s role, such as her title as “Mother of God” (Theotokos), arose later at the Council of Ephesus in 431 AD.
Councils are called when there is a theological dispute that isn’t settled outside and has created too much animosity among believers
The Iconoclastic Controversy (726–843) was related to the outburst of Mohammedanism
Thanks Cronos!