After spending some time over the last few day, I would have to say that it’s a forgery. There are already numerous reasons why explained at the various sites, and I can see why no reputable scholar would want to be associated with giving it any legitimacy. I think it was probably made late 19th or early to mid 20th century, probably some kind of political reasons, what exactly I can’t say. The names of the deities, tribes and the general history regarding the Carpthians and early common era European history is not a stumbling block, but if you read all the planks text. (which was not that easy to find, which makes it even more suspect, just one photo and all the rest you basically have to take on faith, nothing even resembling a clue that it existed previous to the 20th century at all anywhere), the pre-European early common era history is really bizarre and not in line with any other sources whatsoever.
The forgers probably borrowed a lot of the information from Nestors Primary Chronicle, Administrando Imperio and the other known Byzantine, Greek, Roman, Italian and German sources, and then just incorporated it into the tales, but as for going back to the “the land of seven rivers beyond the sea” and related journeys, it’s easily just fiction. The English version text at the link above, (which is strange and includes some retarded edited words added in a few places) has information that is missing from the Serb translated source, a fair amount of text regarding the Czechs and Croats and Rus are missing. This in itself isn’t all that surprising, as I’ve come across numerous instances from Serb sources where it is downright false information, or text added and/or taken away. (I never trust any Serb source I come across until doubled and triple checked at original sources and other scholarly publications, even wikipedia can be tampered with by bored stooges who want to invent histories)
Also, importantly, today we have 20th and 21st century archeological and DNA evidence. DNA evidence trumps all when it comes to the great migrations or any migrations. One source had a few maps drawn up and knowing what we know about DNA alone, it was ridiculous. We know that that the ancestors of todays Slavic speaking nations extends back to 2000 BCE, at least. (See http://scienceinpoland.pap.pl/en/news/news,394140,the-ancestors-of-the-slavs-could-be-in-europe-4-thousand-years-ago.html)
The linear DNA, etymological, topographical, linguistics and physical cultural remains shows that Slavs have been in Europe going very far back, but were called various names. Information regarding the Vistula Veneti, and even many ancient Latin and Greek sources that speak of the Hyperboreans is most likely speaking of at least most of todays Slavs and their languages, if you have some basic history knowledge regarding those times. Without a doubt the earliest sources speaking of the Hyperboreans, even if poetic and regarded as myth at times, have more historical truth than the early history information found in these purported planks. We now know that there were various alliances and cultural exchanges over the last 4 thousand years that would rule out any long journey from the purported locations in the Veles Book, even just DNA evidence alone conclusively shows absolutely no connection to any people in China, Persia, India and those areas. On the other hand DNA evidence does point to the earliest abode of Slavs as possibly being, or at least their furthest eastern locations/eastern migrations,(Tarim Mummies) as being substantially further north of the Caucasus Mountains and Caspian Sea, around the Urals Mountains, which just happens to also coincide with some of the Greek and Latin sources as being the Hyperboreans.
Interesting read, even if fiction, but the parts of the text describing their populations already in Europe I found the most interesting, because those are the parts that line up with all the other sources and information we know, besides we know that todays Slavic speaking nations early history and identities only started coming to the forefront and being more accurately recorded only from the 5th-10th centuries. A proto-Slav, (or photo-Croat/proto-Rus/proto-Pole/proto-Czech etc) from times before 1000 BCE would be speaking something incomprehensible to us today anyway,nobody knows what languages they were speaking, how it could have sounded or what it was called.