The poem "To the Indians Who Died in Africa" is written in the voice of a British soldier speaking to soldiers from the Indian subcontinent. This suggests that the British soldier may have been the commander of a unit of Indian colonial troops, with all of them ordered to fight in a colonial battle somewhere in Africa. Given this background understanding, the statement cited is extremely applicable to the context and theme of the poem.
"This land was not your land, or ours" refers to the fighting that British and Indian soldiers ("foreign men, who fought in foreign places, Foreign to each other") carried out in a place that was foreign to all of them. Each carried with him memories of "his own village." After the war ended, the survivors took back the stories of "action with a common purpose" to tell of those buried in graveyards in the Midlands of Great Britain or in the Five Rivers area of India.