Why is Swedish an official language in Finland?

Related questions

1. What is the culture in Finland?
2. Do Finnish people speak Russian?
3. Does Finland have freedom of religion?
4. Is Finland a secular country?
5. Is Swedish and Finnish similar?
6. Can Finnish understand Swedish?
7. What are the Finnish known for?
8. Is Finland a first world country?
9. What do people in Finland eat for breakfast?
10. How long will it take to learn Finnish?

Tags

1. #language
2. #became
3. #speaking
4. #finns
5. #closer
6. #autonomous
7. #dialects
8. #finland
9. #russian
10. #swedish
11. #official
12. #sweden
13. #spoken
14. #remained
15. #grand
16. #nearby
17. #conquered
18. #parts
19. #linguists
20. #empire
21. #consider
22. #duchy