Who knows three hundred forty three?
שלושה וארבעים ושלוש מאות - מי יודע?
The traditional Passover song "Echad - mi yodeya" implies a possible presupposition that there is a Jewish significance to be found for each natural number. Accordingly, there is an ongoing series on Mi Yodeya that is attempting to unearth significant Judaism facts about each number, in sequence.
What significant Judaism facts are there about the number 343? The more significant within Judaism and the more intrinsically dependent on the value 343, the stronger the answer. Please include sources for your information wherever possible, as with all other answers on this site.
Please don't bring down a rain of lazy gematria answers. I want answers that are genuinely about the number and that also offer up some knowledge about Judaism.