How I think Kamui's dimension works & Tobi/Obito's connection to Madara explained:
Kamui's dimension is kind of like the hyperbolic time chamber from DBZ. In the dimension time is distorted. The user of Kamui can decide the flow of time in the dimension & are able to travel forwards in time, backwards is impossible.
Zetzu is actually from this dimension & Taught Obito how to use his powers.
In Madara's time another Uchiha could use Kamui & had access to this dimension.
Madara was friends with this Kamui user. The Kamui user also helped Madara recover after the battle with the 1st Hokage.
After Madara's loss to Hashirama he wished to be transported to "A time when Hashirama no longer lived", his friend agreed to help. So Madara was transported to a time shortly after Hashirama died.
Realizing the power of Kamui Madara betrayed his friend & stole his eyes. Afterwards Madara gave his Rinnegan eyes to Nagato. He then trapped his 'friend' in Kamui's dimension, But before he could transport himself out of the dimension Madara was stabbed through the heart. After being stabbed Madara used Kamui & traveled to the real world to die. Madara's friend now trapped in an uncontrolled dimension had his physical appearance twisted & changed, his friends name was Zetsu.
Kamui's dimension is kind of like the hyperbolic time chamber from DBZ. In the dimension time is distorted. The user of Kamui can decide the flow of time in the dimension & are able to travel forwards in time, backwards is impossible.
Zetzu is actually from this dimension & Taught Obito how to use his powers.
In Madara's time another Uchiha could use Kamui & had access to this dimension.
Madara was friends with this Kamui user. The Kamui user also helped Madara recover after the battle with the 1st Hokage.
After Madara's loss to Hashirama he wished to be transported to "A time when Hashirama no longer lived", his friend agreed to help. So Madara was transported to a time shortly after Hashirama died.
Realizing the power of Kamui Madara betrayed his friend & stole his eyes. Afterwards Madara gave his Rinnegan eyes to Nagato. He then trapped his 'friend' in Kamui's dimension, But before he could transport himself out of the dimension Madara was stabbed through the heart. After being stabbed Madara used Kamui & traveled to the real world to die. Madara's friend now trapped in an uncontrolled dimension had his physical appearance twisted & changed, his friends name was Zetsu.
