Era beginning/end
The Batrachi Empires rose to power circa −33,500 DR. They out-competed the rising power of the yuan-ti of Mhairshaulk, ensuring they would never achieve the heights of their creators, the sarrukh.
The batrachi were an amphibious race who evolved in the seas, their growth mirroring the sarrukh on land. When they became amphibious, they moved onto the land and supplanted the dinosauroids. The Batrachi Empires rose to power circa −33,500 DR. They out-competed the rising power of the yuan-ti of Mhairshaulk, ensuring they would never achieve the heights of their creators, the sarrukh. The batrachi grew to the height of their power under the wise leadership of Zhoukoudien, the High One. However, their golden age ended abruptly when the High One was killed in battle by Omo, a titan thane of the Jotunbrud Tribes, around −31,500 DR. Around −31,000 DR, the batrachi were losing a war against the titans and desperately enacted a great summoning ritual that unleashed several once-imprisoned primordials. The gods swiftly opposed the primordials. The primordial Asgorath, the World Shaper, even hurled an ice moon or comet at the planet, in order to destroy what she could not have, in an event called the Tearfall. Disastrous earthquakes, fires, and windstorms swept across all of Abeir-Toril, erasing whole continents and rearranging the seas, causing the four Inner Seas to merge into the Sea of Fallen Stars. Ancient sarrukh legends made cryptic mention of the "changing of the stars". But, before the world was destroyed, Ao split it into two twin worlds: Abeir for the primordials and Toril for the gods. At around this time, the first dragons eggs hatched all over Toril, number in the tens of thousands. These were linked to a rain of meteors that fell to Faerûn; at least, the first dragons appeared shortly thereafter. The extreme climate change swiftly led to the end of batrachi civilization. After a cold period called "the seven-turn winter", many batrachi left Toril for the plane of Limbo. Meanwhile, in the seas, the amphibioids appear to have faced pressure from merfolk, sahuagin, and tritons. Their society degenerated and collapsed back into barbarism.