Ancient Slavic astrology and calendar
In the ancient Slavic calendar (Kolyady Dar)
The Krugolets consists of 16 years – 15 common years and one Holy Year
The Circle of Life – 9 Circles of the Year build the Circle of Life (9x16) = 144 years
The Circle of Svarog (or the day of Svarog) consists of 180 circles of life – 25,920 years. During this time, Yarilo-Sun passes one after another through the sky of all 16 Chertogi
In each Chertozh, Yarilo-Sun rises and travels over a period of 1620 years. Svarog, the God of the heavens and a smith, the creator of our world and destiny, set in motion the world of the Rod. Day and night, months and seasons began to alternate.
The runes in the counter-clockwise direction mark 9 days in a week, 9 months of year, and 9 elements (forces) - this is the inner circle. The outer rings of the Ring of Chislobog denote the 16 hours of a day (today it is 24 hours), the 16 months in a circle year, and the 16 halls of the Svarog circle.
The flow of the “River of Life” is the rotation of the Ringlets; a day lasts 16 hours, a rotation of 9 days in a week, a rotation of 9 months in a year, a rotation of 16 years makes a sacred circle, and a rotation of 9 elements in the circle of life. Also, a rotation through the 16 chambers of the Svarog circle.
On the shield of Chislobog, in Svarog's circle, three examples of literacy that the Slavs had before many nations were literate can be seen: Daaryan runes, the Bukvitsa, and Lines and Notches. At that time, writing was figurative and conveyed much more than it does today. The simplified alphabets were meant to change the consciousness of the Slavs, especially the Latin alphabet. However, our wise ancestors, our Gods, knew much more than today's rulers of the world, our people inherited much from storytelling, but greatest lie about the Slavs is that Slavs where illiterate. Our ancestors were very smart, and people capable of many things!
(disclaimer I got all this info from site kolodar.rs)
(I do not promote no one, just sharing knowledge.)