Complex sentence: It wasn't until the explorations and discoveries of Antonio Santander and Gene Savoy in the 1960s and later archeological work by Vincent Lee and research by John Hemming that Espíritu Pampa was generally accepted as the historical Vilcabamba.
Split into simpler sentences: It wasn't until the explorations and discoveries of Antonio Santander and Gene Savoy in the 1960s. Later archeological work by Vincent Lee and research by John Hemming gave further confirmation that Espíritu Pampa was generally accepted as the historical Vilcabamba.