Which of these two options would be considered most elegant / correct? Personally I think Sinicization (or Sinicisation) has a more natural ring to it, but I have seen Sinification used also.
Also, can anyone give an answer as to when either of these neologisms came into usage?
This seems to point directly to Google Ngrams on those words to see what the rest of the (English speaking) world actually does:
I added in the British English spelling, too.
Note that 'sinification' has the longer history, but recently 'sinici[z/s]ation' has become more popular.
To extract a data of word creation from these graphs is a bit iffy; you'd really need to check all the occurrences in the links from that site.
The veribifiers '-ize/-ise' and '-ify' are both productive. I can't seem to tell a pattern in the contexts where one is favored over the other, except that if you're starting with an adjective ending in '-ic', the '-ize/-ise' sounds way better.
Well most of these words seem to use the ise/ize form, e.g.:
There's Russification of course, but I think this is irregular simply because the word Russicisation is rather clumsy.
So, I would go with Sinicisation/Sinicization by default.
Looking at these, both suffixes are very similar. I looked into the meaning of each which are also rather similar. That said, it seems that '-ization'leans more toward changing from one to another where as '-cation' can more often be in an originating process such as fabrication.
Definition of -FICATION from Your Dictionary.com
Origin: Latin -ficātiō, -ficātiōn-, from -ficātus, past participle of -ficāre, to make, from -ficus, -fic.
Definition of -IZE from Merriam-Webster
: cause to be or conform to or resemble : cause to be formed into (2) : subject to a (specified) action (3) : impregnate or treat or combine with b : treat like c : treat according to the method of
: become : become like b : be productive in or of : engage in a (specified) activity c : adopt or spread the manner of activity or the teaching of
