Kythera is situated at a major cross roads of the Mediterranean. The island was (and still is) at the epicentre of a number of major shipping routes to and from Greece from areas such as Italy and Spain in the west, the Black Sea and Asia Minor in the east as well as Egypt, Africa and other Middle-Eastern countries. This means that the island was strategic as both a trading post and port, plus also provided vantage points for attacks on the Greek mainland, particularly the Laconian (Spartan) region.
Kythera is located opposite Cape Malea, one of the most treacherous stretches of the Mediterranean sea, a severe hazard for ancient mariners. This brought brought about certain religious/supersticious behavours. Kythera is also located in an earthquake region, prompting other beliefs by the ancients.
It’s believe that the Phoenicians brought the cult of Aphrodite to Kythera, with Greek worship spreading throughout the Hellenistic from the island. Remains from 7300 years ago indicate that the island was populated at least that far back. Kythera was an outpost for the Minoan thalassocracy from Crete.
After the middle of the 15th c. B.C. the Cretan Minoans seem to have abandoned the island while the Myceneans appear on the scene. During the 14th & 13th c. B.C, that is the Late Bronze Age (Late Helladic III), during which period the Mycenean civilization flourished. Mycenean tablets of that time found in Pylos exhibit Linear B script showing the interesting forms ku-te-ra, ku-te-ra-o, and ku-te-ri-ja, which it is thought refers to Kythera.
To which Mycenean kingdom did Kythera belong? We do not know. In Homer it is mentioned that Agamemnon did not only reign over the plain of Argos but also over many islands whereas Apollodorus mentions that when Atreus’ brother, Thyestes, was expelled he went to Kythera. So, it is possible to assume that the Argive Myceneans controlled the island.
In the period of the so-called Dorians, i.e the period of the Dark Ages are particularly dark for Kythera. Neither the sources nor the archaeological finds so far provide any evidence. It is a fact that during this period or a bit earlier the cult of Aphrodite was introduced by the Phoenicians who took advantage of the crumbling Mycenean kingdoms or more likely, had established on the island centres of craftsmanship/commercial bases for the production and trading of the purple (porphyra) which was their main produce for export. After such produce, the island in Antiquity was named as Porphyris (ο αμφορέας με την Πορφύρα).
Here’s a great video about Kythera from 1987.
Here’s some links to photos and video taken in Kythera by Tzeli Hadjidimitriou.