What is the significance of Amitav Ghosh's work, The Shadow Lines?

The Shadow Lines, by Amitav Ghosh, looks at the existence of arbitrary physical boundaries between countries and between cultures. It examines how the culture of violence binds as it attempts to separate. Although the topic is thought-provoking, the book is written in simple language which allows the reader to understand the author’s point of view.
Through the narrator, the author examines how culture, families, and ideas can transcend the physical boundaries that form the borders of countries. His family life was changed when the border between India and Pakistan was altered, but it was also affected when he loses his friend and distant relative, Tridib, during a mob uprising. The story follows the narrator as he travels from India to London and back.
He begins to realize that Shadow Lines cannot divide or bind a people. It is the shared culture and history of people that brings them together in spite of lines of demarcation between them. Toward the end of the book as the family travels from Calcutta to their previous home in Dhaka, the grandmother inquires about the border. She wants to know how they will be aware of crossing the boundary if there are no physical demarcations. The narrator faces the realization that it is the only cultural differences, and family beliefs which transcend any physical boundary. The author is making the point the lines on the map between countries are simply Shadow Lines for political and geographic reasons.
The pervasive culture of violence during revolution is also examined in this book. Ghosh asserts that the acts of violence that are meant to separate people on either side of the Shadow Lines actually unite them in human emotions and feelings. People on both sides of the hard won borders feel hatred, loss, and sadness. He says,
They had drawn their borders, believing in that pattern, in the enchantment of lines, hoping perhaps that once they had etched their borders upon the map, the two bits of land would sail away from each other . . . What had they felt, I wondered, when they discovered that they had created not a separation, but a yet-undiscovered irony - the irony that killed Tridib: the simple fact that there had never been a moment in the four-thousand-year-old history of that map, when places like Dhaka and Calcutta were more closely bound to each other than after they had drawn their lines . . .
No matter how many lines are drawn on a map, the borders are simply shadow lines that cannot transcend memory or imagination, which are part of a person’s identity. In the story, the grandmother believes in these lines until the end, while the younger, well-travelled, Ila, mindlessly crosses borders every time she travels. The grandmother admonishes that nations draw their borders with the blood of those who fought for them. Any border can be crossed over and over again using your imagination. It is only in your memories and cultural beliefs that these borders truly exist.