according … Jeremiah: Daniel likely had a copy of Jeremiah’s prophecies.
the desolation of Jerusalem would last seventy years: Jerusalem was destroyed in 586 BC (see 2 Kings 25:8), and the first return happened in 538 BC. This was about 48 years later. They began rebuilding the city almost immediately (see Ezra 3:1–13; Isaiah 44:28), and the rebuilt temple was completed in 515 BC. This was about 71 years after its destruction (Ezra 6:15). Daniel might have considered Jerusalem’s “destruction” as starting with his own exile in 605 BC (see Jeremiah 25:11–12), with 67 years between 605 and 538 BC.