Which century did St Cyril name the Russian alphabet?

St. Cyril, along with his brother St. Methodius, developed the Glagolitic alphabet, which is considered the precursor to the Cyrillic alphabet. This occurred in the 9th century, specifically around the 860s. The Cyrillic alphabet, named after St. Cyril, was later developed in the 10th century, primarily for the Slavic peoples, including the Russians.