As I write about the spread of Hinduism, Sanatana Dharma, I wondered about two points.
There is no doubt that the Sanatana dharma of Hindus spread far and wide throughout the world is indisputable considering the archeological finds found throughout the world indicating the presence of Sanatana Dharma.
Two questions remain.
How did people travel so far?
Secondly how did they fight the wars with the foreign invaders when it happened?
Though Puranas and Ithihasa speak of what appears to be beyond the Human capacity of crossing the ocean by flying, there are references that the ancient knew about Ships and warfare.
While one may question how Hanuman could fly over the Ocean to Lanka, Valmiki in the same breath talks of ships!
When Hanuman was crossing the ocean to Lanka, he was compared to a ship tossed by winds on the high seas. Sugriva speaks of Sumatra, Java and even the Red Sea, when sending forth his monkey hosts in the quest of Sita.
This only means that though the people during Ramayana knew of ships, yet Hanuman chose to fly.

The Rig Veda mentions “merchants who crowd the great waters with ships”.
The Ramayana speaks of merchants who crossed the sea and bought gifts for the king of Ayodhya.
Manu legislates for safe carriage and freight by river and sea.
In some of the earliest Buddhist literature we read of voyages ‘out of sight’ of land, some lasting six months or so.
“There was also extensive intercourse of India with foreign countries, including the Mediterranean lands and the African continent, naturally led to piracy on the waters. There then arose the need for the protection of sea-borne trade, and we are told that “at the outset the merchant vessels of India carried a small body of trained archers armed with bows and arrows to repulse the attacks of the pirates, but later they employed guns, cannon and other more deadly weapons of warfare with a few wonderful and delusive contrivances.”
–William Vincent pp. 457). These are probably the beginnings of the ancient Indian navy. in The Commerce and Navigation of the Ancients In the Indian Ocean.
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The navy is one of the angas (part) of the complete army. Examples of ships being used for military purposes are not lacking. When Vidura scented danger to Kunti’s five sons, he made them escape to the forest with their mother, crossing the Ganges in a boat equipped with weapons having the power of withstanding wind and wave.(Mahabharata Shanti Parva 59,41)
Darius launched a maritime expedition under Skylax of Caryanda to the Indus Delta, and during Alexander’s time, again, we read of the people of the Punjab fitting out a fleet. We have the testimony of Arrian to show that the Xathroi (Kshatri), one of the Punjab tribes, supplied Alexander during his return voyage with thirty oared galleys and transport vessels which were built by them.
-Herodotus 517 BC, India and Its Invasion by Alexander p. 156.
By regular practice one becomes an adept in fighting from chariot, horses, elephants and boats, and a past-master in archery.”
-Kamandaka (XVI, 50)
“Boats should be employed for military purposes when the theatre of hostilities abounded in water.
(Manu Samhita Vii 192)
‘The Admiralty as a department of the State may have been a creation of Chandragupta but there is evidence to show that the use of ships and boats was known to the people of the Rg Veda. ”
Early History of India, Vincent Smith P.133.
This exploit you achieved, Asvins in the ocean, where there is nothing to give support, nothing to rest upon, nothing to cling to, that you brought Bhujya, sailing in a hundred oared ship, to his father’s house.
Further on in the Veda, this same vessel is described as a plava which was storm-proof and which presented a pleasing appearance and had wings on its sides. Another reference informs us that Tugra dispatched a fleet of four vessels (Catasro navah) among which was the one referred to above. We may infer from these passages that the Asvins were a great commercial people having their home in a far-off island, and that their ruler Tugra maintained a fleet in the interests of his State. There are also other references in the Rg Veda to show that the ancient Indians were acquainted with the art of navigation. For instance, Varuna is credited with a knowledge of the ocean routes along which vessels sailed.
The Baudhayana Dharmasastra speaks of Samudrasamyanam and interprets it as nava dvipantaragamanam, i.e. sailing to other lands by ships. This very term occurs in the navadhyaksa section of the Kautaliya Arthasastra.
The Puranas have several references to the use of ships and boats. The Markandeya Purana speaks of vessels tossing about on the sea. The Varahapurana refers to the people who sailed far into the ocean in search of pearls and oysters. The ships floated daily on the shoreless, deep and fearful waters of the ocean. We are on firmer ground when we see in the Andhra period their coins marked with ships. The ship building activities were great on the east coast, and the Coromandel coast in particular. From this period to about 15th century A.D. there was a regular intercourse with the islands of the Archipelago most of which were colonized and also with ancient America right across the Pacific as testified to us by the archaeological finds and inscriptions in those parts.
The Pali books of Sri Lanka like the Mahavamsa refers to ocean going vessels carrying 700 passengers. Such frequent intercourse and colonization through the ages could not have been effected without a powerful fleet.
“Turning to the history of South India, we have evidence to show that the country had trade and culture contacts with foreign countries like Rome in the west and Malay Archipelago and South east Asia in the east. Yavana ships laden with articles of merchandise visited the west coast frequently. There was active foreign trade between Tamil Indian and the outer world at least from the time of Soloman, i.e. about 1000 B.C. Roman historians refer to the commercial intercourse that existed between Rome and South India. In the first century before Christ we hear of a Pandyan embassy to Augustus Caesar. (refer to Periplus translated by Schoff p. 46).
The Sangam classics point to the profession of pearl-diving and sea-fisheries on a large scale. We hear of shipwrecks of the early Tamils saved now and then by Manimekhalai, the goddess of the sea.
(Note: ancient Tamil tradition traces its origins to a submerged island or continent, Kumari Kandam, situated to the south of India. The Tamil epics Shilappadikaram and Manimekhalai provide glorious descriptions of the legendary city and port of Puhar, which the second text says was swallowed by the sea.
As in the case of Dwaraka, (please refer to chapter on Dwaraka and Aryan Invasion Theory), initial findings at and off Poompuhar, at the mouth of the Cauvery, show that there may well be a historical basis to this legend: apart from several structures excavated near the shore, such as brick walls, water reservoirs, even a wharf (all dated 200-300 B.C.), a few years ago a structure tantalizingly described as a “U-shaped stone structure” was found five kilometers offshore, at a depth of twenty-three meters; it is about forty meters long and twenty wide, and fishermen traditionally believed that a submerged temple existed at that exact spot. If the structure is confirmed to be man-made (and not a natural formation), its great depth would certainly push back the antiquity of Puhar.
Only more systematic explorations along Tamil Nadu’s coast, especially at Poompuhar, Mahabalipuram, and around Kanyakumari (where fishermen have long reported submerged structures too) can throw more light on the lost cities, and on the traditions of Kumari Kandam, which some have sought to identify with the mythical Lemuria…
We have the account of a Cera King conquering the Kadamba in the midst of sea waters. The Cera King Senguttuvan had a fleet with which he defeated the Yavanas who were punished with their hands being tied behind their backs and the pouring of oil on their heads. The Cholas also maintained a strong fleet with which they not only invaded and subjugated Lanka but also undertook overseas expeditions. Among the conquests of Rajaraja, Lanka was one, and his invasion of that island finds expression in the Tiruvalangadu plates, where it is described as follows:
“Rama built, with the aid of the monkeys, a causeway over the sea and then slew with great difficulty the king of Lanka by means of sharp-edged arrows. But Rama was excelled by this (king) whose powerful army crossed the ocean in ships and burnt the king of Lanka.”
Citation.
http://www.bibliotecapleyades.net/vimanas/esp_vimanas_11b.htm
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