Background
She was daughter of King Casimir III of Poland (1309–1370), who was succeeded, not by Anna nor any of Casimir"s own descendants, but by Casimir"s nephew, King Louis I of Hungary.
Elector of Brandenburg Duke of Teck
She was daughter of King Casimir III of Poland (1309–1370), who was succeeded, not by Anna nor any of Casimir"s own descendants, but by Casimir"s nephew, King Louis I of Hungary.
Anna"s mother was Casimir"s fourth wife Hedwig of Sagan (d 1390). Anna"s elder half-sisters were already dead though one of them had left children. Anna was the eldest child of that fourth marriage, which did not either produce any sons to King Casimir"s dismay.
They had a single surviving child, a daughter known as Anna of Cilli (1386–1416).
In 1394 the widowed Anna married Ulrich, Duke of Teck (died 1432). Meanwhile, the throne of Poland had passed in 1386 to Jogaila, Grand Duke of Lithuania.
Duchess Anna desired to regain Poland for her heirs, the descendants of Casimir III, and to obtain power in her homeland. She gave birth to a daughter, Hedwig Jagiellon, in 1408.
In 1421 Anna"s granddaughter was betrothed to the future Frederick II, Elector of Brandenburg (1413–1471), the second son of Frederick I, Elector of Brandenburg.
Anna died in 1425, which left Hedwig without any strong relatives to support her position. Because Hedwig died (allegedly poisoned) in 1431 without any issue, Anna"s descent became extinct before Jogaila"s death in 1434.
A party of Polish nobles, including Anna, wanted Hedwig and her intended husband to succeed Jogaila at least in Poland, instead of her half-brothers, his sons by Sophia.