  Aims. Historical records provide evidence of extreme magnetic storms with
equatorward auroral extensions before the epoch of systematic magnetic
observations. One significant magnetic storm occurred on February 15, 1730. We
scale this magnetic storm with auroral extension and contextualise it based on
contemporary solar activity. Methods. We examined historical records in East
Asia and computed the magnetic latitude (MLAT) of observational sites to scale
magnetic storms. We also compared them with auroral records in Southern Europe.
We examined contemporary sunspot observations to reconstruct detailed solar
activity between 1729 and 1731. Results. We show 29 auroral records in East
Asian historical documents and 37 sunspot observations. Conclusions. These
records show that the auroral displays were visible at least down to 25.8{\deg}
MLAT throughout East Asia. In comparison with contemporary European records, we
show that the boundary of the auroral display closest to the equator surpassed
45.1{\deg} MLAT and possibly came down to 31.5{\deg} MLAT in its maximum phase,
with considerable brightness. Contemporary sunspot records show an active phase
in the first half of 1730 during the declining phase of the solar cycle. This
magnetic storm was at least as intense as the magnetic storm in 1989, but less
intense than the Carrington event.
