Origins of the Uzumaki Clan

Kushina
Kushina was born in the Land of Whirlpools. A land known for ninjas with powerful sealing techniques known as fūinjutsu. The Uzushiogakure, ninja from the Land of Whirlpools, were often employed to seal jinchūriki, tailed demon beasts, into suitable hosts. Their fūinjutsu was so incredibly feared it caused of a level of paranoia that led other countries to constantly attack the Land of Whirlpools. Uzumaki Kushina was born during these warring times which influenced her personality to constantly strive for a future of peace. Her naturally strong life force and enormous amount of chakra made her a primary successor for the host of the Nine-Tailed Fox, Mito Uzumaki. She is eventually moved to Konohagakure, became the second host of the Nine-Tailed Demon Fox, and enrolled in the Konohagakure's ninja academy.
Kushina's Time in Konohagakure

Kushina and Minato
During Kushina's early development as a kunoichi, she was often teased by other students with names like Tomato because of her vibrant red hair and round cheeks. Her only friend was Minato Namikaze, the eventual 4th Hokage, a young ninja close to her age whom she called "wimpy" on first impression. Uzumaki Kushina dreamed to become the first female Hokage and continued to grow into a beautiful and skilled ninja with a tomboyish personality. She was known for her fūinjutsu and was quite physically strong which earned her the title Red Hot-Blooded Habenero. Along with her progression as a ninja, her relationship with Minato grew as well. One day, Kushina was kidnapped by shinobi from the Land of Lightning and was rescued by Minato. He was the only ninja clever enough to follow Kushina' trail of red hair she left while in captivity. Minato told Kushina he was able to find her because of her trail of beautiful hair. Kushina's hair was never the target of compliments so she was immediately taken aback and fell in love with Minato along with her hair.
The two lovers eventually married and Kushina became pregnant. Minato and Kushina decided on the name Naruto, the main character in Jiraiya's first novel. At first Jiraiya protested because the name was a product of random thought while eating ramen. Kushina believed the name Naruto was beautiful and insisted on the name Naruto.
Her Demise
As Minato Namikaze became the 4th Hokage and Naruto impending birth, Konohagakure made plans. Kushina's predecessor, Mito Uzumaki, warned her that during labor the seal containing the Nine-Tailed Fox severely weakens. This would leave her open to attack and other countries would attempt to steal the demon sealed in her. Madara Uchiha did exactly that and held Naruto hostage as soon as he was born. Minato manages to rescue Naruto but was forced to momentarily forsake Kushina in order to save their son. Madara took advantage of the situation and released the Nine-Tailed Demon Fox. He quickly subdued the demon and unleashed it on Konoha. Minato saves Kushina and places her next to the newly born Naruto at their home. As Minato returns to the battlefield to engage the Nine-Tailed Demon Fox, Kushina joins him and attempts to reseal the demon back into her. The plan is protested by Minato and seals the Demon Fox into their son, Naruto knowing he will persevere through the persecution he will endure for hosting a demon inside of him. This process is presumably what kills Kushina as she gives up a large amount chakra in the process.
Kushina's Continued Support of Naruto

Minato, Naruto, and Kushina
Many years later, Naruto tries to control the Nine-Tailed beast inside of him and almost fails. His mother, Kushina, saves him and helps her son control the Nine-tailed demon. She also discovers Naruto inherited a similar verbal tic she possessed, something she didn't want to pass on. Kushina tended to end her sentences with "(da)ttebane" and Naruto similarly ended his sentences with "(da)ttebayo". As Kushina tells Naruto she is ready to move on she tells him she loves and reveals the events she had experienced.