Traditionally rwandans (for many centuries) used to tell time based on the signs in the nature such as sunshine, moonlight, crock, cattle daily movements, birds etc. From the colonial area, they have been intoduced to a different way of telling time using a new device called "watch". In the process of telling they used the Swahili language which was the main colonial means of communication. Later on they mixed both Kinyarwanda and Swahili. For example: They would say 'saa cumi kinyarwanda) or saa kumi' (Swahili). Rwandan calender uses special names of months as indicated in this unit.