|Out of universe information|
Ran was born before the Asgard had begun cloning. She had also become an ascended being. Prior to ascending, she had a natural, ancestral body of the Asgard, even having hair- she's even the same size or slightly taller than modern Asgard.
When Elizabeth Weir saved Doctor Rodney McKay and her involvement, Ran sent Weir back to her physical form on the planet Mazatla, where she could get help. She made it so that Weir was allowed to keep her memories, but that they would come back in fragments. (SGA: "Unascended", "The Third Path")
When Dis, along with the Vanir, hoped to reach Ran, who was born before the Asgard began with cloning, to contact her to access her deupphöjda, to use her DNA and eggs that- which they believed held the key to saving their race from extinction. The Vanir tried to get Ran using an Ancient machine, they also attempted to have her fix their damaged DNA, and possibly extract the knowledge she's learned as an ascended being.
However, the Vanir caught a previously ascended Doctor Elizabeth Weir (Ran had ascended Weir) with the intention of contacting and forcing Ran to help them, but Weir suggested merely asking the ascended being to help them. Believing it was impossible to ascend themselves, Dis admitted that the Vanir never considered that Ran would happily return to mortal form to assist them. Weir and Daniel pointed out that rules which the ascended follow are flexible enough for Ran to perhaps help them without having to descend. (SGA: "Unascended", "The Third Path")
After Weir proposes Dis use a shrine made by the Ancients on Earth to communicate with Ran; the Vanir agree to use an old Asgard scout ship and travel to Earth. At the shrine Dis is able to contact Ran and makes an appeal- Ran answers by returning to mortal form, with the belief that extermination of her race trumps the lofty rules. However, Ran knew that if she descended, she would probably not be able to ascend again. She warns Dis that even with her help the Vanir may have done too much genetic damage to be spared, yet if they the degradation can be reversed they still may not get what they want. Dis accepts this saying "this is more hope than they have had for a thousand years."
Ran and Dis depart and then return to the Pegasus galaxy aboard an Asgard scout ships, leaving the SGC team to return to Earth with the Puddle Jumper that they had brought aboard the scout ship. With that, the Vanir depart promising not to cause any more problems for the Pegasus galaxy. Instead, they will focus on saving their race. (SGA: "Unascended", "The Third Path")