This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
Q: Passage: While most of mainland Greece and the Aegean islands was under Ottoman control by the end of the 15th century, Cyprus and Crete remained Venetian territory and did not fall to the Ottomans until 1571 and 1670 respectively. The only part of the Greek-speaking world that escaped long-term Ottoman rule was the Ionian Islands, which remained Venetian until their capture by the First French Republic in 1797, then passed to the United Kingdom in 1809 until their unification with Greece in 1864.[page needed] Question: The Ottomans controlled what islands b y the end of the 15th century?
A:
Aegean islands