jumping-off place

1. A beginning point for a journey or venture.
2. A very remote spot.

1.  A starting point for a journey or venture, as in This tiny village is the jumping-off place for our trek into the desert. This usage probably alludes to jumping into the water. [Early 1800s]
2.  A very remote spot; also, the last place to be reached. For example, This was the jumping-off point for the first gold miners in Alaska. [Early 1800s]

Jumping-Off Places, the towns along the border of American frontier settlement where emigrants completed their outfitting for the journey across the Plains during the 1840s and 1850s. Independence, Mo., was the best known of these places. Among the others were Council Bluffs, Iowa; Saint Joseph, Mo.; and Fort Smith, Ark.

Bibliography

Faragher, John Mack. Women and Men on the Overland Trail. New Haven, Conn.: Yale University Press, 1979.

The noun has one meaning:

Meaning #1: a place from which an enterprise or expedition is launched
  Synonym: jumping-off point