By 907 the Great Moravia had already been disintegrated, either due to the inner conflicts or the invasion of Magyar tribes, or both. By 11th century, the Slavs living in the area of the present-day Slovakia were gradually being integrated into the Hungarian kingdom. This was the main factor that contributed to the dispersal of the Czech-Slovak sprachbund, but for it, the two would have probably never dispersed.

Due to the fact that the people within the Hungarian kingdom were not linguistically suppressed, the Slovak dialects managed to survive to this day. And this is where we get to another pure myth - the so-called thousand-year lingual suppression. The lingual suppression took place in late-19th/20th centuries, no one suppressed us in middle ages. The myth was probably created by Slovak nationalists. Had we been suppressed for thousand years, we would all speak Magyar today, not Slovak.

STANDARDISATION PROCESS
The standardisation process began in 17th century, but the most important events date from 18th and 19th centuries. In 1787 Anton Bernolák made a first semi-successful attempt to standardise the language, but it was only accepted by the Catholic party of Slovak scholarship. The basis for his language was a dialect used on the academic field of the University of Trnava, which was some kind of modified western dialect. A few charachteristics set his language apart from the modern form, for instance the absence of J grapheme, since his language used for the phoneme J the G grapheme. Another characteristic is the lack of palatalisation present in the central dialects or eastern dialects, most notably ť, ď, ň, ľ, which made the language sound harder than the current form.

In 1843 another form was codified by evangelist Ludevít Štúr and other scholars. Due to the fact that they were 'patronised' by Bernolák's contemporary and catholic Ján Hollý, this form managed to unite the evangelic and catholic parties. The basis of the language was a dialect spoken around Martin, which according to Štúr was free of any foreign influence. The dialect itself was highly palatalised, which made it sound quite soft.

In 1852 the final form of Slovak was formed due to the publication of a Concise Grammar of Slovak by Martin Hattala. This included the y-i distiction and the palatal L sound (soft L - Ľ) and many other features.
The Slovak language has since changed a little, but Štúrian Slovak language is still considered to be almost an equivalent to the modern standardised form with minimum differences.

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NOTES:
sprachbund - a language union
urheimat - the original homeland of a proto-language
proto-language - the original, oldest form of a certain language group/family
PGmc - Proto-Germanic language
OCS - Old Church Slavonic language

'Slavic' and 'Slavonic' are synonyms