I believe it is Mills Creek waterfall but I’m not sure...
The angle of the waterfall gives the answer away
The name of the river that marked the northern boundary of Islamic expansion in central Asia is Oxus. In 651, Arabs took Iran. After this, they went towards the Oxus river in the north with the intention of defeating the Turkish. The Arabs succeeded and the expansion setling Oxus river as the northern boundary was finally consolidated in 750 C.E.
When Germany sunk the Lusitania this made the United States enter WWI. In the first world war Germany was the main aggressor.