Why are Greek cultures referred to as "Hellenistic" and Chinease as "Sino"? Are these Latin?
The Greek word for 'Greece' is
Hellas, and its people are
Hellenes. The original area called
Hellas was small, just north of Delphoi, and associated with the Amphiktonic Council that later developed into one of the major religious institutions of Greece. It was only this area that
Hellas referred to during the Homeric age, but during the dark ages and archaic period the word
Hellene gradually began to encompass all Greeks. By the classical period this was more or less common usage. There's also speculation that it may have originated from the roots for
our own people in one of the old Hellenic dialects, but I wouldn't know much about that.
Anyway, so Hellas/Hellenes, it's a quick step from there to Hellenistic. The Romans called the Greeks
Graeci (sometimes) and the region in which they dwelt usually some variant on
Achaea, which only refers to a part of the Peloponnesos (Achaea being both the site of one of the major groups Homer uses to refer to all of the 'Greeks' in the
Iliad and
Odyssey, and the center of a third- and second-century BC united southern Greek federal league that was destroyed by the Romans in 146 BC). So it wouldn't have been them.
Hellenistic, fwiw, refers to the period between the conquests of Alexander the Great and the end of the last Hellenistic kingdoms of Ptolemaic Egypt and Baktria/the Indohellenic kingdoms, both falling around the end of the last century BC. (Though there is convincing numismatic evidence that one or more may have survived past the attested birth of Christ, namely Straton II. Though since the names of the
Stratoi are in such flux, it's really impossible to say which number he may have had.

)
Sino- does refer to a Latin word, but I think it may have had a Greek origin as well. Not nearly as clear on that.