The Convergence

Deep in the south-Pacific ocean a slight anomaly was noticed by AI and machine-learning computers focused on studying ocean patterns, currents and fluid dynamics. These patterns were first noticed in the late 21'st century, and attributed largely to climate change. Over the course of the following 20-30 years these patterns continued to intensify.
The true beginning of the Convergence is unknown. It was only in the late 21st century that mankind had the machine learning tech to dig through the mass amounts of data needed to pry subtle patterns from the fluid dynamics in the Pacific Ocean, let alone differentiate a new pattern and flow in a small and vacillating area.
The area in the Pacific, which shrinks and grows in size from a noted 5 miles to as large as 30 miles in diameter continued to have distinct currents and fluid dynamics that sometimes seemed to be affected by the surrounding water and in other moments seemed to exist completely separate from the ocean around it. Because the area shrinks and grows, because the shifts in current and patterns waver it is completely unknown when this phenomena truly began, all we know is it started to be noted by machine-learning tools in the late 21st century.
The Convergence continued to be monitored, over the course of the following 10 years -into the new century- its differentiated patters grew more pronounced, and became more distinct from the currents and fluid dynamics of the surrounding waters. Within the first twenty years of the new century the Convergence became completely distinct from the waters around it, like an enormous glass tube had isolated a vast chunk of the Pacific ocean. It's changes in current and pattern, which by this time entire AI and machine learning banks had been dedicated to its discover, observation and prediction noticed a very odd change in its currents and patters.
The pattern was becoming more and more pronounced, but remained the same. Like a melody playing all in the same octave suddenly keeping the same notes, but jumping up and down octaves.
On July 17, 2147 what is only assumed to be a massive, global-spanning electro-magnetic pulse knocked out all electronic devices worldwide. Millions died, billions more lost massive amounts of their lives in the ensuing months. Governments and people strove to replace these structures, but the pulse seemed to have irrevocably altered Earth's magnetic fields, making further use of electronics impossible. The pulse is also widely assumed to be the cause of people gaining magical powers, Descension followed shortly after, tho no one knows when the first cases were found due to the lack of any magical record keeping and the loss of electronic record-keeping.
By 2163 the world had generally recovered alot of its structures, replacing electronic devices, services, and tools with magical ones. Cars, phones, the internet were all beginning to come back online with magical means and tools.