Middle-Eastern and European J2aJ2a's strong presence in Italy is owed to the migration of the Etruscans from the Near East to central and northern Italy, and to the Greek colonisation of southern Italy.
The Phoenicians, Jews, Greeks and Romans all contributed to the presence of J2a in Iberia. The particularly strong frequency of J2a and other Near Eastern haplogroups (J1, E1b1b, T) in the south of the Iberian peninsula, suggest that the Phoenicians and the Carthaginians played a more decisive role than other peoples. This makes sense considering that they were the first to arrive, founded the greatest number of cities (including Gadir/Cadiz, Iberia's oldest city), and their settlements match almost exactly the higher frequency zone of southern Analusia.
The Romans surely helped spread haplogroup J2 within their borders, judging from the distribution of J2 within Europe (frequency over 5%), which bears an uncanny resemblance to the borders of the Roman Empire.
The world's maximum concentrations of J2a is in Crete (32% of the population). The subclade J2a4d (M319) appears to be native to Crete.