@mokka,
We have known each other since childhood because we used to live in the same neighborhood. (You still know one another, there is nothing in your narrative which requires an anterior past tense.) In 1998 we became close friends for a year and half. (There is no reason to use the semicolon--i can't think why you put it there.) I was 24 and she was 18 years old. However, due to the war
between Ethiopia and Eritrea, I left Eritrea in January, 2000,
so we separated. Surprisingly, we met again on Facebook in 2011, while I was living in Saudi Arabia.
The sentence about you leaving Eritrea may be made more coherent by saying: However, I left Eritrea in January, 2000, due to the war between Ethiopia and Eritrea, and we were separated.