When in Jewish history did the Sages instruct people to play musical instruments during the Three Weeks?

This source-based Torah study examines the question: When in Jewish history did the Sages instruct people to play musical instruments during the Three Weeks? The canonical Hebrew discussion develops the issue through the weekly Torah portion and the sources cited there, preserving the distinctions, tensions, and practical implications of the original text. This localized discovery layer does not add any new halakhic, medical, legal, scientific, historical, theological, or empirical ruling or claim beyond the canonical Hebrew source.