The history of the Siberian cat can be approached in two stages: the second stage centers mainly around the development of the modern Siberian cat as we know it today. This started around 1987 after the first cat show in Russia and the beginning of the development of the Siberian as a pedigree breed.
But prior to this time - one might say ages before this time - the Siberian cats were already pretty well-known in Russia. Before breed standards and feline pedigrees, they were known mainly as "the fluffy cats" to Russians. This is a natural breed that adapted and evolved over time to their natural environment, in relative isolation to cat populations from other regions (i.e., "landrace"). It is thought to be closely related to the Norwegian Forest Cat, and is even said to be the ancestor of all modern long-haired cats, though it is more probable that all modern long-haired cats such as the Angora and the Persian share the same ancestors with the Siberian. The Siberian, though, certainly evolved in its own unique way - by acclimatizing itself to the cold and snowy Russian climate.
The Siberian is ancient, and the earliest records of this magnificent cat can be traced back to as early 1000 AD. Since then, they have figured prominently in the popular consciousness of the local population - in Russian folktales and fairy tales, they were known as protectors of the elderly and of children, and are able to open gateways to magical realms. Many were feral, or existed in the wild, others were strays, while there were some domesticated Siberians that grew close to their adoptive families and dutifully performed mouse catching duties.
Interestingly, the name "Siberian" is a bit of a misnomer. Perhaps it has to do with some of the folklore associated with this natural breed - as cats that were said to have descended from wild forest cats from the dense, snowy forests of the taiga, or as cats that guarded the monasteries in Siberia during the Middle Ages. Or perhaps it was the unique, triple coat that one easily associates with the severe snowy climate of Siberia. There is no actual evidence or documentation, in any case, to show that the Siberian cats originated from Siberia, or were endemic to North East Russia, as they were could be seen pretty much everywhere in the country. Among the stray cats, those with thicker and waterproof coats had better chances of surviving the climate, so these were naturally more prevalent.
But no one can really point to a specific breed that can be characterized as a "Siberian." One interesting anecdote is post-war Leningrad after the 872-days siege. The city was devastated, and many of the population, including the cats, died of hunger and cold. It was fertile ground for the invasion of rats, which people later sought to counter by bringing in cats from all over the USSR. These cats of all possible types mixed, including, of course, the long-haired fluffy cats known as the Siberian. Though the mixture of thousands of these cats naturally resulted in many different types.
In the 1980s, the cat fancy hit Russian and the USSR, and shows took place in large cities such as Riga, Moscow, and Leningrad. Many people poured into these shows, bringing along their cats, and various breeds were identified among these household pets, but of course, nobody could consider them purebreds yet. And so the idea for Russian cat breed was born. Naturally, it had to be a distinctive cat, and while "Siberian Cats" were certainly considered, nobody could pinpoint what precisely were the Siberian cats among the local cat population. The efforts at developing the Siberian cat as a distinct breed were undertaken by different cat breeders and fanciers, but it was the Kotofei Club, through its president Olga Mironova and assisted by Irina Katzer, that wrote and publicized the first written standard for the breed. This standard was based on two very well-known Siberians: Mars, a blue lynx point and white; and Roman - a brown tabby and white.
Since 1988, the shows brought in foreign judges and cat fanciers, people took great interest in the Siberian, and thus paving the way for the worldwide popularity of this breed. The Siberian's recognition by many of the cat organizations in the world are still fairly recent, owning to the somewhat prohibitive cost of exporting these cats from Russia, including export limitations due to limited breeding stock, the breed is still comparatively rare elsewhere in the world. In the United States, the first Siberians were imported by Mrs. Elizabeth Terrell of Baton Rouge, Louisiana, and David Boehm of Hackensack, New Jersey in 1990. It wasn't until 2002 that the breed came to Britain, and to Australia in 2003, from the US. Catteries, cat clubs, and can enthusiasts in Russia and all over the world have helped to promote their popularity all over the world.
Today, the Siberian cat is the national cat of Russia.