The 'Tailed' Beasts, an incredibly feared force at this time as their power was completely unknown. After the first few years since the first Bijuu sightings things begun to get serious after the first major incident. Half of Iwagakure was wiped out during the Four Tailed's spontaneous rampage through the village. This was the first time anything as such had occurred and thus they were undoubtedly unprepared for the full wrath of this beast. The Third Tsuchikage was furious and called upon a summit meeting of all the Village Leaders at the time. During the incident all the other villages hadn't chosen to intervene until they begun to fear that they would be directly affected once the Bijuu was done with Iwa. This was the reason they all met, to sign a Treaty that would ensure that actions would be taken in order to aid each other. Rather than defend themselves alone once the Bijuu decided to attack they decided it was better to all work together and go on the offensive to capture all the Bijuu.

After 30 long years the villages had finally had enough experience with Bijuu to begin capturing and containing them. After yet another decade the first Jinchurikki was born, a Kumo Shinobi now imbued with the Eight Tailed Hachibi. Not long after almost all the Bijuu had been captured and sealed within Jinchurikki from different villages. All except One. The Five Tailed Gobi had rarely been sighted before and had not been seen at all in the recent years. At first it had been thought that the Beast's Speed ability was the reason it was able to avoid both capture and detection, but the truth was far more alarming. It seemed as though Iwa had been getting more and more audacious since the first attack on their village. The Gobi had in fact been captured many years before my the Fourth Tsuchikage who believed that the village was entitled to have weaponised Jinchurikki to protect themselves in case one of the other villages lost control of their own Hosts. This did not bode well with some of the other villages that thought that maybe the Tsuchikage's intentions weren't as transparent as he made them. Fearing the Fourth Tsuchikage would use the power of the Gobi to attempt to expand their influence, the First Kazekage decided it would be best if the Tsuchikage was allowed to keep such power for himself. This sparked the Great War. 

The battle between two of the largest villages Iwa and Suna had been waging strong for about half a decade with no sign of dying down. The war had gotten so large that unfortunately the Rain Village, Ame, had become completely engulfed in a fight they had no stake in. It was becoming much more dangerous as the war drew closer to Konoha and soon after they decided to intervene. At this point Konoha and Kiri had been mutual allies so when the Fourth Hokage joined the war he had the Third Mizukage backing him and his forces. With Kazekage's forces already fighting the Tsuchikage's and vice versa, they didn't have much chance defending off the combined force of Konoha and Kiri. Suna and Iwa's forces quickly begun to fall as the battle begun to draw far too close to their own villages once again, this was when the Hokage decided to end the war before there could be more casualties and a Second Summit was called. 

It took almost 15 years for the Tsuchi and Kazekage to finally agree upon taking part in a Second Summit at which point the war had died down with a tremendous amount casualty from both villages. The Summit was held in the ruins where Amegakure once stood tall. A new agreement was made, this is a summarised version;
:: Experiments looking to weaponise Jinchurikki were now forbidden
:: All Bijuu must be sealed within suitable Hosts, accounted for and monitored
:: There would be annual report sent to and fro' each village informing on each Jinchurikki's status
:: No Village single Village could have control of more than 2 Jinchurikki 
:: Villages with more than 3 Jinchurikki at the time would have to migrate the Host
:: Until further knowledge on the Bijuu, letting the Beast free would be considered a serious crime

The war had completely died out in the following months but there was always some animosity between Suna and Iwa to a point that the Kazekage prohibited Iwa ninja from visiting the village without real important reasons. The War was over but most certainly never forgotten.

A recent faction of 'Nukenin (Missin's Ninja)' now referring to themselves as 'Rokunin' has emerged believing the Bijuu's power should not be left in the hands of the Jinchurikki and their Village leaders. They believe people with power had already proved they couldn't be anything but insatiable during the last Great War and thus no-one should own the Bijuu. The original Founder of the group Hashin Karasu was killed by an Iwa assassin shortly after the group's influence begun to grow. He had left one last message to all those that fought for their cause, "No Bijuu or Jinchurikki would be left standing and all those that opposed the Rokunin would suffer the same fate."