“From Aceh in the far north-west to Torres Strait in the east is 5000 miles, almost as far as from London to Baghdad. The Archipelago has 14,000 islands, some mere equatorial rocks, others some of the largest in the world.” This description best fits

The quoted passage describes the vast Malay/Indonesian Archipelago extending from Aceh (north‑west Sumatra) eastward to the Torres Strait near New Guinea — a sweep characteristic of Indonesia rather than the West Indies, Japan or the Philippines. Wallace and related accounts treat this region as the Malay Archipelago encompassing major islands such as Sumatra, Borneo, Java and New Guinea, and many smaller islands arranged in island groups and arcs [2]. Geologically, both the Indonesian and Philippine archipelagos lie along active plate margins and were formed by ocean‑ocean convergence and subduction, explaining the numerous volcanic and coral islands noted in the passage [1]. Torres Strait’s position separating New Guinea from Australia further anchors the eastern limit of this archipelago [3].

Sources

1. [2] https://people.wku.edu/charles.smith/wallace/arwbooks/xx_Wallace_Malay_Archipelago_1869Harper.pdf
2. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 8: Convergent Boundary > Formation of The Indonesian Archipelago > p. 112
3. [3] https://www.britannica.com/topic/worlds-largest-islands-2228256