What was significant about the discovery of gallium

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."

in the 1950s, country music came into its own before rock-n-roll took off in the 60s while jazz and classical music continued to innovate