IVC bricks and Vedic Fire Altars: A brief overview of Indian Geometry
I read a post/comment here which suggested a relationship between brick making traditions of IVC and Vedic Fire Altars described by Sulbasutras. Intrigued, I went down a rabbit hole and found extremely interesting history of Ancient Indian Geometry. Think of this as a beginner friendly introduction rather than an actual academic study.
Standardisation of Bricks in IVC
Standardisation of bricks in the ratio of 1:2:4 is one of the hallmark feature of Indian Valley Civilisation. This standardisation occurred in the early stages as evidenced from the sites of Kot Diji and Harappa. This ratio varied particularly in the eastern sites such as Kalibangan and Banawali, wherein the ratio of 1:2:3 was observed. It is only during the mature stage(2600–1900 BCE) of IVC, we find that ratio was standardised across the length and breadth of the civilisation. During the Late phase, brick dimensions diverged away from the Indus proportion.
So, what were the brick sizes in the IVC sites? Although the ratio of 1:2:4 was standardised, Harappan people used different brick sizes, e.g 7×14×28 cm, 8×16×32 cm, 9×18×36 cm, and 10×20×40cm. Kenoyer observes a gradual decrease in the size of bricks from the earliest to the last phase at Harappa. While during the earliest phase, the size of bricks was 7×14×28 cm, it decreased to 5×12×24 cm at the end of the Harappan phase. Also, The larger brick sizes were used prominently for the construction of fortification walls around the settlements.
A sidebar, Interestingly IVC people may have used a combination of binary and decimal system. Weight measures doubles in ratio as 1,2,4,8,16,32,and 64, after which it progresses in decimal system like 160,200,320,640,1600. Hemmy believes that it shows that there was no sexagesimal system(base60) and all the ratios are binary or decimal.
Complex Geometry of bricks in Vedic Altars
This is probably more complex to analyse and here I'll be limiting myself to Baudhayana Sulbasutras(800-500BCE) which is considered to be the oldest, largest, and mathematically most rich text providing precise geometric rules for measuring and constructing ritual fire altars(vedis).
Before getting ahead, attaching a brief introduction of units of measurement used by Baudhayana Sulbasutras.
Angula, a unit of measure, is equal to 14 grains of anu plant(Panicum milaceum) or alternatively it is equal to 34 sesame seeds put together with their broad sides. (B.SL.S 1.4-5)
Various brick sizes explained in Baudhayana Sulbasutra are:
- A square brick whose side measures fourth part of a Purusa (120 ang.), called caturthi. 30×30 ang (B.SL.S 3.11)
- A square brick whose side measures fifth part of a Purusa, called pancami. 24×24 ang (B.SL.S 3.11)
- A square brick whose side measures sixth part of a Purusa. 20×20 ang (B.SL.S 3.11)
- A square brick whose side measures tenth part of a Purusa. 12×12 ang (B.SL.S 3.11)
Caturthi and variations created out of it,
- A right triangle brick created by diving the caturthi brick in half via diagonal, called ardha. 30×30×30sqrt(2) ang. Here, 30sqrt(2) is the hypotenuse of the triangle. (B.SL.S 4.2-3)
- A right triangle brick created by diving the caturthi brick in quarter via diagonals, called padya. 15sqrt(2)×15sqrt(2)×30 ang. Here, 30 is the hypotenuse of the triangle. (B.SL.S 4.3-4)
- A rectangular brick whose one side measure half of caturthi and other one quarter of caturthi. 15×7.5 ang. (B.SL.S 4.5-7) (Type 1)
- A right triangle brick with two equal sides measuring half of caturthi. 15×15×15sqrt(2). Here, 15sqrt(2) is the hypotenuse of the triangle. (B.SL.S 4.5-7) (Type 2)
- Combination of Type 1 and Type 2 Brick to create a trapezoid brick. 22.5×15sqrt(2)×7.5×15 ang. (B.SL.S 4.5-7) (Type 3)
- Combination of two Type 3 bricks to create a pentagonal brick. 7.5×15sqrt(2)×15sqrt(2)×7.5×30 ang. Bricks of this kind are called Hansmukhi. (B.SL.S 4.5-7)
Pancami and few variations created out of it, (there are more variations here too but keeping it short here)
- A rectangular brick whose one side measures pancami and other side is longer than the pancami side by half. 36×24 ang (B.SL.S 3.42-43)
- A rectangular brick whose one side measures pancami and other side is half of pancami. 24×12 ang (B.SL.S 3.44)
Sulbasutras has given specifications for the height of the brick as well. The height of the bricks should be equal to fifth part of the janu (32 angulas) = 6 2/5 ang. The height of the bricks for the top layer (Pancacoda and Nakasata type) can be half of the regular brick (3 1/5 ang). (B.SL.S 2.58-59) Definition of Pancacoda and Nakasata layer is given in B.SL.S 2.28.
It is using these various kinds of bricks, different types of Vedic Fire altars are created. Baudhayana Sulbasutra describes in detail how to construct different types of altar, square shaped, circular, triangular and most renowned the falcon/bird shaped altar.
Major differences between the two traditions
| Aspect | IVC Bricks(2600-1900BCE) | Baudhayana Sulbasutra Bricks (800-500BCE) |
|---|---|---|
| Purpose | Focussed on practical applications. Used in Houses, drainage, fortifications, public works. | Constructed for Vedic ritual altars. |
| Material | Mostly baked bricks, both sun baked and kiln baked; Mud bricks in earlier stage. | Both baked and unbaked bricks, depending on the ritual |
| Standardisation | Highly standardised ratio of 1:2:4; Variations have been observed. | Multiple specially shaped bricks designed according to geometric and ritual rules. |
| Design | Mostly rectangular | Rectangular, square, triangular, trapezoidal, pentagonal, and other custom shapes. |
| Basis | Engineering, urban planning, and modular construction. | Ritual geometry and religious symbolism |
Evidence of Continuity
Currently there is no scholarly consensus that the Sulbasutra brick specifications were derived directly from Indus Valley brick standards or were related in anyway. Both are considered to belong to different historical and cultural contexts.
Most scholars argue that chronological gap between the two traditions, close to 1000 years, makes direct continuity difficult to demonstrate without intermediate evidence. There is also lack of direct archaeological and textual evidence to link Harappan brick making traditions with the ritual brick traditions described in the Sulbasutras.
Proponents of continuity contest that continued usage of baked bricks and a strong emphasis on measurements and proportions imply some form of technological and cultural continuity. Additional evidence is required to establish direct continuity.
Conclusion
Most historians and archaeologists take cautious stand regarding the debate. It is speculated and agreed that brick making technology may have persisted after the decline of Indus Valley Civilisation; however, they do not conclude that both the brick traditions are continuous. With current evidence, there is no conclusive evidence establishing a direct link between IVC brick making traditions and Vedic brick traditions described in Sulbasutras.
Sources:
[1] https://dn760108.eu.archive.org/0/items/in.ernet.dli.2015.405552/2015.405552.Baudhayan-Sulbasutram.pdf (Do let me know if other translations are available)
[2] https://www.researchgate.net/publication/235784941_Bricks_and_urbanism_in_the_Indus_Valley_rise_and_decline
[3] https://www.researchgate.net/publication/348836370_Evolution_of_Early_Human_Settlements_in_the_Sarasvati_River_Basin_Archaeological_Evidence_and_Site_Distribution_Analysis
[4] https://aws-static.iicdelhi.in/s3fs-public/2020-11/145615June132013_IIC_48_13_06_2013.pdf