The Siege of Mandalore was a major conflict depicted during a four episode arc in Ursa Wren, Sabine's mother
Sabine Wren (Tiya Sircar) is one of the main characters of the animated series Rebels, raises the question of how old Sabine was during the Siege of Mandalore.
In season 1 of Star Wars Rebels, audiences see their first Empire Day, a celebration of Palpatine's Galactic Empire. The show's protagonist, Ezra Bridger, turned 15-years-old on Empire Day and according to Star Wars Rebels: The Visual Guide, Sabine is 16 years old at the start of Rebels, making her roughly 2-years older than Era. That would mean she was born around 21 Before the Battle of Yavin, which would make Sabine 2-years-old during the Siege of Mandalore, an event that happened in 19 BBY.
As Sabine isn't mentioned, though, there's no indication of whether or not she was on Mandalore, or in Sundari, where the conflict took place. However, it's very likely that she and her older brother Tristan were in hiding with their father during the siege. Unlike her mother, Sabine's father Alrich was not a warrior but an artist, and Sabine has credited her talents to him. Despite the efforts of Ahsoka, Bo-Katan, Ursa, and many others, Order 66 and the rise of the Empire meant that control of Mandalore eventually ed to Imperial forces after the Siege. Sabine was recruited into the Imperial Academy there and was a willing cadet, suggesting she didn't much of the Siege of Mandalore, but eventually grew disillusioned with the Empire.
In Star Wars Rebels, after Sabine was denounced by her family for speaking out against them, Alrich was taken as a political prisoner by the Empire to ensure the rest of his family would comply. As a man who "fights with his art" rather than with weapons, it's very possible that the Wren clan were safe on their ancestral home of Krownest during these final episodes. Although both Rebels and Star Wars: The Clone Wars have ended, fans are hoping the live action series The Mandalorian will continue Sabine's story.