I already read Mixed Unit Tactics, Interview with Three Booksellers and some other books, but I wan't to know more about it. Why it actually started? Did it ended (I know that Khajiit kinda won it, but whats the situation now)? And what does the words mean "Bosmer and Khajiit share too much to leave each other alone." said in the Interview with Three Booksellers said by Jobasha? What do they share?

Have you read Dance In Fire? I believe it follows something similar or that.

Sarelis,

Let me attempt to dispel some of your confusion. The five year war you speak of started during the rule of Jagar Tharn due to a border dispute between the Khajiit and the Bosmer (specifically an attack on the Khajiit city of Torval). It has officially ended by the Oblivion crisis, but border skirmishes doubtlessly continue as they have for the preceding millennia.

The Bosmer and Khajiit share a common ancestry: Azura turned some Aldmer into Khajiit while Y'ffre turned them into Bosmer.

Thanks for the explanation, and I am going to read Dance In Fire right now.

But the war actally started because the bosmer where tired of khajiti bandits invading their lands, and then the bosmers invaded torval...

Dance in the Fire is a Morrowind book and Jagar Tharn was long before the Nerevarine so it officially ended a long time before Oblivion, but that does not mean that there are no Border skinrmishes even now. Decimus went to Valenwood because others had been there and failed to secure the contracts. Those others had been travelling around for some time and making quite a reputation for themselves. So it may be that Dance in the Fire is set after the end of the War when people were thinking about how to rebuild and there was skirmishing going on even then.