Whilst the identity of Malachi, the man, is subject to some debate, it is accepted in the Christian, and more importantly the Jewish tradition, that his prophecies were the last recorded in the Hebrew Bible.
‘The Talmud teaches, “After the last prophets Chaggai, Zechariah, and Malachi died, the Divine Spirit of prophetic revelation departed from the Jewish people.” ‘(Who Was the Prophet Malachi? – Chabad.org)
Of course, the story of Israel continues. It is a story of invasion and suppression. The invading army of Alexander the Great. The Seleucid empire. The Ptolemies. These regimes brought not only waves of terror and suppression to the Jewish people, but also exposed them to Greek influences which filtered throughout the Jewish culture. Ultimately these invaders were superceded by the Romans. Whilst again and again throughout this period the hand of God is evident in the preservation of His people, it is beyond doubt that when the voice of Malachi fell silent, so also the voice of prophecy.
400 years of incredible violence and turbulence. 400 years of the most profound and protracted silence.
And then, in the wilderness, ‘John appeared.’